NT01 conference

A - Accepted contributions.

Prof. Jerry Bernholc
NC State University
Department of Physics
Box 8202, 127 Stinson Dr.
Raleigh, NC 27695-8202
USA
+1-919-515-3126 (phone)
+1-919-515-7331 (fax)
------------------------------------------------------------
Title: Theoretical studies of quantum transport, pyro- and piezo-electric effects and lithium intercalation
Authors: J. Bernholc, M. Buongiorno Nardelli, J.-L. Fattebert, V. Meunier, C. Roland, and Q. Zhao
Affiliations: Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
Abstract:
We have investigated the electronic and quantum transport properties of bent, deformed and tapered nanotubes, as well as nanotube-metal contacts, which will likely form components of future nanotube-based devices. Bent armchair nanotubes keep their metallic character up to fairly high angles, while metallic chiral nanotubes open a sizable gap at the Fermi level, indicating that they can be used as nanoscale strain sensors. Tapered armchair tubes remain metallic, while their zigzag counterparts are semiconducting, as expected. Ballistic transmission is very sensitive to interactions with the substrate and coupling to the contacts. Our {\em ab initio} calculations for NT/Al structures show substantial charge transfer and rehybridization effects, which strongly affect the quantum conductance. We have also investigated BN nanotubes that are intrinsically polar. For BN tubes in chiral or zigzag structures, the symmetry permits a pyroelectric field along the tube axis, which is of the order of kV/cm per nanotube. The pyro- and piezo-effects will likely be useful in nanoscale switches, resonators, actuators, and transducers. Turning to Li intercalation in carbon nanotubes, we have shown that Li cannot penetrate nanotube walls unless 9-fold rings or larger openings are present. Our large simulations Li motion lead to aggregation in the interstitial channels.
Dr. Ruth Pachter
US Air Force Research Laboratory
Materials & Manufacturing Directorate
AFRL/MLPJ, 3005 P St. Suite 1
Wright-Patterson AFB, Ohio 45433-7702
USA
(937)255-3808x3177 (phone)
(937)255-1128 (fax)
------------------------------------------------------------
Title: A Density Functional Theory Study of Single Wall Nanotubes
Authors: Ruth Pachter, Zhiqiang Wang, W. Wade Adams, Air Force Research Laboratory, Materials & Manufacturing Directorate, Wright-Patterson AFB, OH 45433-7702; Brahim Akdim, Ohio Supercomputer Center, Columbus, OH 43212
Affiliations:
Abstract:
In our continuing efforts to design multi-functional materials with tailored properties we report a density functional theory study of single wall carbon nanotubes with different diameters and chiralities. Carbon nanotubes are modeled as either one-dimensional or three-dimensional periodic systems in the simulations, corresponding to an isolated tube or a rope. Calculated structural and physical properties of carbon nanotubes and related systems will be discussed, in comparison with other theoretical work and experimental data.
Prof. Alain ROCHEFORT
CERCA
5160, boul. Decarie, #400
Montreal, Quebec H3X 2H9
Canada
514-369-5214 (phone)
514-369-3880 (fax)
------------------------------------------------------------
Title: Influence of Length on the Electrical Transport into Metallic, Semiconducting, and M-S Junction Carbon Nanotubes.
Authors: Alain Rochefort
Affiliations: Centre de recherche en calcul appliqué (CERCA)
Abstract:
One of the most important findings of carbon nanotubes (CNTs) research is that the current in semiconducting tubes can be switched by an external electric field which allows semiconducting tubes to be used as the channel of field-effect transistors (FETs). So far, the NT segments used in the FET experiments have been relatively long, in the order of several hundred nm to a micron. However, the process of device miniaturization aims primarily at reducing the channel length. The question then arises if short nanotube devices can preserve the operational characteristics of long devices. We have investigated theoretically the influence of the length on the electrical properties of two general types of CNT named metallic (M) and semiconducting (S) tubes, and a third type made of both M and S tubes called a M-S junction. We compare the variation of electronic and electric properties with the length of NTs in a 0-20 nm range. The electronic structure calculations on M and S CNTs clearly show a transition from 0-D (molecular) to 1-D (wire) between 2.5 and 5.0 nm. The changes are more subtle for the M-S junction due to the electronic structure mismatch between the M and S segments at the interface. The variation of electrical transport properties are discussed in terms of the presence of discrete molecular orbitals in short CNTs, the contribution of electron tunneling, and to the presence of metal-induced-gap states (MIGS).
Dr. Tapas Kar
Utah State University
Department of Chemistry & Biochemistry
0300 Old Main Hill
Logan, UT 84322-0300
USA
1-435-797-7230 (phone)
1-435-797-3390 (fax)
------------------------------------------------------------
Title: BN substituted carbon compounds: A theoretical study
Authors: Tapas Kar*, J. Pattanayak and S. Scheiner
Affiliations: Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300
Abstract:
Previous theoretical and experimental investigations on B/C/N systems are mostly concentrated on 50:50 combinations of C and BN units, i.e., BC2N stoichiometry. In the present theoretical investigation we will replace one by one pair of carbon atoms by isoelectronic BN unit. Successive replacement patterns, structure, stability, nature of bonding and electronic properties of such hybrid materials are discussed.
Dr. Tapas Kar
Utah State University
Department of Chemistry & Biochemistry
0300 Old Main Hill
Logan, UT 84322-0300
USA
1-435-797-7230 (phone)
1-435-797-3390 (fax)
------------------------------------------------------------
Title: Theoretical investigation on the insertion of Li+ into Carbon Nanotubes
Authors: Tapas Kar*, Jayasree Pattanayak and Steve Scheiner
Affiliations: Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322
Abstract:
Theoretical investigations have been carried out to explore the possibilities of Li ion intercalation or insertion through the side-wall of single-wall carbon nanotube. Hartree-Fock, MP2 and density functional theories with minimal to extended basis sets were used to estimate the potential energy surface (PES). The barrier to insert Li ion through these rings depends on the ring size. Insertion is easier as the ring size increases. Li ions favors two positions: a) inside the tube closer to the wall, and b) outside of the tube. Atomic charge distributions/redistribution in different location of Li+ of the tubes are discussed.
Mr. Peter R Butzloff
University of North Texas
Department of Materials Science
P. O. Box 305310
Denton, Texas 76203
USA
(817) - 280 - 3197 (phone)
(817) - 278 - 3197 (fax)
------------------------------------------------------------
Title: A New Hybrid Nanocomposite formed by Intercalation of Multi-Walled Carbon Nanotubes into Epoxy Swelled Montmorillonite Clay
Authors: Peter Butzloff (1, 2), Nandika Anne D'Souza (1), Yi Sun (3, 4)
Affiliations: (1) University of North Texas Department of Materials Science P. O. Box 305310, Denton, TX 76203, (2) Bell Helicopter Textron, Fort Worth, Texas 76101, (3,4) Nanocs Incorporated, 37-26, 62nd Street, Woodside, NY 11377, (4) Department of Chemistry and Center for Advanced Materials and Nanotechnology, New York University, New York, NY 10003
Abstract:
Mechanical reinforcement of polymers using randomly oriented Multi-walled Carbon Nanotubes (MWCNT) has shown limited benefits due to localized polymer matrix strain. To overcome this difficulty we investigated combinations of MWCNT and ion exchanged montmorillonite layered silicates in an epoxy polymer. Mechanical reinforcement was examined using Dynamic Mechanical Spectroscopy. Similar dispersion problems are expressed by MWCNT and layered silicates due to charge mediated flocculation. Dispersion was achieved using an organic electron donor solvent. Particle surface interaction then took place at the bound surfactant on the silicate platelet. Intercalation of MWCNT between the layered silicates was imaged using Scanning Electron Microscopy (SEM). The connected fiber architecture was shown to mitigate polymer strain damage by nanotubes. Particle orientation in the hybrid composite was observed on curing in a 6kV electric field. This demonstrated that control of the hybrid composite microstructure was possible to further develop strength, damage resistance, fracture toughness, and polymer film barrier properties.
Dr. Richard Martel
IBM T. J. Watson Research Center
Route 134

Yorktown Heights, NY 10598
USA
914-9452164 (phone)
914-945-4531 (fax)
------------------------------------------------------------
Title: Single wall nanotube field-effect transistors and logic circuits
Authors: R. Martel, V. Derycke, C. Lavoie, P. Wong, and Ph. Avouris
Affiliations: IBM T. J. Watson Research Center
Abstract:
One of the most interesting applications of carbon nanotube involves their use as active channels of field-effect transistors (FETs) [1]. The transconductance of these early devices was small (10^{-9} A/V), limited by the resistance of the contacts. We will present new results on nanotube FETs with optimized performance. We found that the "on" and "off" currents as well as the transconductance of the devices depend strongly on the properties of the junction between the source-drain metal and the nanotubes. By optimizing this geometry using carbide contacts, we have achieved several order of magnitude higher transconductances and the carrier mobilities now exceed 100 cm^{2}/Vs. These devices show bipolar transport (p- and n-type) resulting from the weak Fermi-level pinning of the contacts. The detail of the transport mechanism in these devices will be presented. Their characteristics will also be benchmarked with the silicon MOSFET and shown to be comparable. Finally, we demonstrated the fabrication of various logic circuits based on nanotubes using complementary p- and n-type nanotube FETs. [1] S. J. Tans et al. Nature 393, 49 (1998); R. Martel et al. Appl. Phys. Lett., 73, 2447 (1998)
Dr. Maria J Lopez
Universidad de Valladolid
Dpto. de Fisica Teorica
Facultad de Ciencias
Valladolid, 47011
SPAIN
34-983-423147 (phone)
34-983-423013 (fax)
------------------------------------------------------------
Title: Transformation of Single-Wall Carbon Nanotube ropes into Multiwall Carbon Nanotubes
Authors: Maria J. Lopez(a), Angel Rubio(a), Julio A. Alonso(a), Sylvie Bonnamy(b)
Affiliations: (a) Dpto. de Fisica Teorica, Universidad de Valladolid, 47011 Valladolid, Spain; (b) CRMD, CNRS-Universite, 1B rue de la Ferollerie, 45071 Orleans Cedex 2, France
Abstract:
Recently it has been discovered that bundles of single-wall carbon nanotubes (SWCNT's) transform into multiwall carbon nanotubes (MWCNT's) under thermal treatment at high temperatures (2300 K-2500 K). The MWCNT's produced by such a transformation contain from 2 to 6 nested tubes. To investigate this "showy" structural transformation of the tubes, from SWCNT ropes into MWCNT's, we have performed extensive molecular dynamics (MD) simulations using semiempirical potentials to mimic the Carbon-Carbon interactions.We propose a possible mechanism for this transformation based on the "concerted" coalescence of the tubes in the bundle. The roles played in the structural transformation by the size of the tubes as well as by their chiralities are analyzed.
Prof. David Tomanek
Michigan State University
Department of Physics and Astronomy
Michigan State University
East Lansing, Michigan 48824-1116
USA
+1-517-355-9702 (phone)
+1-517-353-4500 (fax)
------------------------------------------------------------
Title: Formation mechanism and packing of nanotube peapods
Authors: Savas Berber, Mina Yoon, and David Tomanek
Affiliations: Michigan State University
Abstract:
We investigate the absorption process and the packing geometry of fullerenes in nanotubes and peapods using molecular dynamics simulations and structure optimization techniques. To understand the way a fullerene enters a nanotube to form a ``nano-peapod'', we investigate the absorption dynamics of a C$_{60}$ molecule in a (10,10) nanotube either through the open end or a large opening in the tube wall. The underlying Linear Combination of Atomic Orbitals total energy functional is based on {\it ab initio} calculations. Our results for the C$_{60}$@(10,10) system suggest that the most efficient absorption occurs through defects in the tube wall, within a narrow launch velocity window that corresponds to the experimentally observed optimum temperature range for peapod formation. In an open system containing fullerenes and peapods, the energy gain associated with fullerene entry into the tube exposes the encapsulated fullerenes to an internal pressure which can amount to a fraction of one GPa. This pressure reduces the inter-fullerene separations, and could be used to compress other substances within the tubes.
Prof. David Tomanek
Michigan State University
Department of Physics and Astronomy
Michigan State University
East Lansing, Michigan 48824-1116
USA
+1-517-355-9702 (phone)
+1-517-353-4500 (fax)
------------------------------------------------------------
Title: Scroll-to-nanotube transformation: The zipper mechanism
Authors: Savas Berber and David Tomanek
Affiliations: Michigan State University
Abstract:
Using total energy calculations, we investigate the relative stability of multi-wall nanotubes and graphitic scrolls, as well as a possible conversion in-between these structures. We show that scroll segments, consisting of rolled-up graphite sheets, may coexist with segments consisting of nested tubes within a single tube, separated by a dislocation region. Energy considerations suggest that such dislocations may easily be created at the elevated temperatures during nanotube formation. We also propose a bond-rearrangement mechanism that allows an axial zipper-like motion of the dislocation, thus converting a scroll into a multi-wall nanotube segment, or vice versa. Due to the low energy cost of the zipper motion, and in view of the instability of a scroll with two unsaturated edges along the axis, we find that a scroll-to-nanotube conversion is energetically favorable and may proceed even at room temperature, unless hindered by defects.
Dr. László P. Biró
Research Institute for Technical Physics and Materials Science
P. O. Box 49
Budapest, H-1525
Hungary
+36-1-3922681 (phone)
+36-1-3922226 (fax)
------------------------------------------------------------
Title: ROOM TEMPERATURE GROWTH OF SINGLE WALL COILED CARBON NANOTUBES AND Y-BRANCHES
Authors: L. P. Biró*, R. Ehlich#, Z. Osváth*, A. Koós*, Z. E. Horváth* and J. B.Nagy@
Affiliations: *Research Institute for Technical Physics and Materials Science, H-1525 Budapest, P.O.Box 49, Hungary, #Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Str.2A, 12489 Berlin, Germany, @Facultés Universitaires Notre-Dame de la Paix Rue de Bruxelles, 61 Namur, B-5000, Belgium
Abstract:
The growth of carbon nanotubes from fullerene fragments produced by catalytic decomposition in the presence of transition metals at about 450 °C was investigated. The nanotubes are grown by vapour deposition on highly oriented pyrolytic graphite (HOPG) at room temperature. No further purification or manipulation is necessary for investigations by scanning tunneling microscopy. The templating effect of the substrate is assumed to be an important growth condition. No tubes were found on Au(111) or mica surfaces. Individual tubes as well as raft like structures of multiwalled tubes and bundles of single walled tubes were on HOPG. Several cases of Y- branching of single wall carbon nanotubes were observed with an angle of approximately 120° between the branches and a branch diameter of about 1.6 nm. Tightly wound „telephone cable-like" coils were found too.
Dr. Shekhar Subramoney
DuPont Company
Experimental Station
P. O. Box 80228
Wilmington, DE 19880-0228
USA
(302) 695-2992 (phone)
(302) 695-1351 (fax)
------------------------------------------------------------
Title: Scrolls and Nested Structures in Multiwalled Carbon Nanotubes
Authors: Shekhar Subramoney1, Gerry Lavin1, Rodney Ruoff2, David Tomanek3, Savas Berber3
Affiliations: 1DuPont Company, Central Research and Development; 2Northwestern University, Mechanical Engineering Department; 3Michigan State University, Physics Department
Abstract:
Since multi-walled carbon nanotubes (MWNT) were discovered about a decade ago there has been considerable interest in their structural intricacies, growth mechanisms, and electrical and mechanical properties. The tips and closure structures of MWNT have been the topics of intense scrutiny. Recent analysis of defect structures along the tube walls shows that most MWNT are complex structures composed of scroll-like and nested features existing side-by-side. Within the nested tubes, helicity changes little from layer to layer, and depends only on layer diameter. Such an analysis should lead to a better understanding of the unique properties of carbon nanotubes.
Dr. Petr Kral
The Weizmann Institute of Science
Department of Chemical Physics
Rehovot , 76100
Israel
972 (8) 9342012 (phone)
972 (8) 9344123 (fax)
------------------------------------------------------------
Title: Tribo-Effects in Nanotubes
Authors: Petr Kral
Affiliations: The Weizmann Institute of Science
Abstract:
I discuss new tribo-effects in nanotubes, as induced by light and friction with fluids. First, I complement our recent work [1], showing that atoms intercalated in C nanotubes can be driven by a dc electric current, which is generated optically by mixing one and two-photon interband electron transitions. In particular, I show [2] that in heteropolar BN nanotubes, monochromatic laser beam can generate electric currents of orientations controlled by the structure of nanotubes. These currents are accompanied by ultrafast mechanical expansions of the BN nanotubes. Finally, I show that electric currents can be induced in metallic nanotubes immersed in flowing liquids [3]. Here, the friction between molecular layers and the nanotube generates an asymmetrical flow of phonons in the nanotube, which can drag free carriers. These new phenomena have potential photo-electric and photo-mechanical applications. I discuss also other photo-effects in nanotubes, which we have studied recently. [1] P. Kral and D. Tomanek, Phys. Rev. Lett. 82, 5373 (1999). [2] P. Kral, E. J. Mele and D. Tomanek, Phys. Rev. Lett. 85, 1512 (2000). [3] P. Kral and M. Shapiro, Phys. Rev. Lett. 86, 131 (2001).
Prof. Reshef Tenne
Weizmann Institute
Department of Materials and Interfaces
Rehovot, 76100
Israel
+972-8-9342394 (phone)
+972-8-9344137 (fax)
------------------------------------------------------------
Title: Hollow nanoparticles of WS2 as superior solid lubricant
Authors: L. Rapoport, V. Leshzinsky, I. Lapsker, M. Lvovsky, Yu. Volovik, R. Rosentsveig, Y. Fedman and R. Tenne
Affiliations: Holon Academic Institute of Technology and the Weizmann Institute of Science
Abstract:
Recently, inorganic hollow nanoparticles of metal dichalcogenide MX2 (M=Mo,W,etc.;X=S,Se) with structure related to nested carbon fullerenes and nanotubes (designated inorganic fullerene-like materials - IF) have been developed. It has been shown that IF possess superior lubricating properties over solid lubricants with lamellar structures, like graphite and MoS2 (2H platelets). We attribute the recently reported outstanding tribological behavior of IF-WS2 to its chemical inertness and to the hollow cage structure, which leads to high elasticity and allows the particles to roll rather than slide (rolling friction) in appropriate loading regimes. Unfortunately, the slippery nature of these nanoparticles leads to their fast displacement from the contact area, and consequently the efficacy of their lubrication is maintained so long as they can be replenished to the contact area. By confining the IF nanoparticles inside a porous and densified solid matrix, prepared by powder metallurgy (PM) techniques, slow release of the IF nanoparticles onto the metal surface alleviates both friction losses and wear, while assuring the mechanical integrity of the composite. A multiscale tribological model is proposed, according to which the nanoparticles reside in the pores and are furnished to the surface where they serve as both a lubricant and spacer. The potential ramifications of this work for self-lubricating bearings, gears, etc. are also discussed.
Mr. Gunnar Moos
Fritz-Haber-Institut
Department of Physical Chemistry
Faradayweg 4-6
Berlin, 14195
Germany
+49/30/8413-5505 (phone)
+49/30/8413-5377 (fax)
------------------------------------------------------------
Title: DYNAMICS OF LOW ENERGY OPTICAL EXCITATIONS IN SWNTS: COOLING OF A LASER HEATED ELECTRON GAS AND NONEQUILIBRIUM EFFECTS
Authors: G. Moos^{1}, R. Fasel^{2}, T. Hertel^{1} and G. Ertl^{1}
Affiliations: ^{1} Fritz-Haber-Institut der MPG, Department of Physical Chemistry, Faradayweg 4-6, 14195 Berlin, Germany,^{2}EMPA Dübendorf, Überlandstr. 129, 8600 Dübendorf, Switzerland
Abstract:
We present a time-domain study of the relaxation of electronic excitations in SWNT- and HOPG-samples at lattice temperatures between 40 K and 320 K. Time-resolved photoemission is used to probe the dynamics of the optically excited electron gas. A detailed analysis of the Fermi-edge in the photoelectron spectra is used to determine the increase and lowering of the electron-gas temperature after optical excitation of the sample by a visible femtosecond laser-pulse. The cooling of the electron-gas is intimately related to the coupling of electrons to lattice vibrations and can be used to measure the electron-phonon coupling strength. Such energy transfer between electrons and lattice may also contribute to current induced failure in SWNTs. We find that the observed temperature decay at different lattice temperatures is consistent with dominant electron-lattice energy-transfer by back-scattering from longitudinal acoustic phonons. Certain features in the photoemission spectra, however, cannot be attributed to the dynamics of a thermalized electron gas and indicate a dynamic shift of the electrochemical potential. The magnitude and direction of this shift can be related to the sample density of states and derivative at the Fermi level.
Prof. Mildred S. Dresselhaus
MIT
77 Mass Ave
Cambridge, Massachusetts 02139
USA
617-253-6827 (phone)
617-253-6864 (fax)
------------------------------------------------------------
Title: Single Carbon Nanotube Raman Spectroscopy
Authors: M.S. Dresselhaus, Ado Jorio, G. Dresselhaus, and R. Saito
Affiliations: MIT, University of Electro-Commun., Chofu, Tokyo, Japan
Abstract:
The very sharp one-dimensional density of electronic states in small diameter single wall carbon nanotubes and the strong electron-phonon coupling allow observation of the Raman spectra from one single wall carbon nanotube when the incident or scattered photon is in resonance with an interband transition $E_{ii}$ between singularities in the joint density of states between the valence and conduction bands. Observation of the Raman spectra of the radial breathing mode from an individual nanotube is used to provide a definitive identification of its structure through determination of the $(n,m)$ indices. Variations of this basic method for different cases are discussed. This information is further used to determine to high resolution the profile of the joint density of states near a van Hove singularity. Because of the high sensitivity of the electronic, transport, vibrational and other nanotube properties to the structural $(n,m)$ indices, this non-destructive, readily available characterization technique is expected to have a significant impact on current basic research on carbon nanotubes.
Dr. Pavel Nikolaev
G.B.Tech / NASA JSC
P.O.Box 58561, Mail Stop C61

Houston, TX 77258
USA
281-483-5946 (phone)
281-483-1605 (fax)
------------------------------------------------------------
Title: Length measurements and dispersion of isolated single-wall carbon nanotubes
Authors: Pavel Nikolaev \dagger , Sivaram Arepalli \dagger, William Holmes \dagger , and Bradley Files \ddagger
Affiliations: \dagger G. B. Tech./NASA-Johnson Space Center, 2101 NASA Road One, Houston, TX 77058, USA; \ddagger NASA-Johnson Space Center, 2101 NASA Road One, Houston, TX 77058, USA
Abstract:
Nanotube length and effects of subsequent purification are important with respect to the critical length and stress transfer issues in nanotube-based composites. This work focuses on the length of single wall carbon nanotubes (SWNTs) produced by the pulsed laser vaporization technique, and effects of processing (purification, sonication) on it. Nanotube length was measured by AFM on pristine nanotube specimens as well as after sonication. In each case great care was taken to measure individual nanotubes, rather than bundles. Pristine nanotubes were collected on quartz substrates placed directly in the laser oven and exposed for 0.5 s. Their length is in excess of 20 \{mu}m, and their location and size distribution allowed us to conclude that nanotubes form very close to the target and continue to grow and bundle up in collisions as they travel away from it. Several nanotube specimens from various sources were deposited on silicon after extensive sonication. Nanotubes vary in length from 250 to 500 nm, which confirms that sonication cuts them. Issues of nanotube solubilization will also be discussed.
Dr. Stephan Roche
Commissariat a l'Energie Atomique, DRFMC/SPSMS
17 rue des Martyrs
Grenoble, 38054
FRANCE
33-4-76-88-33-81 (phone)
33-4-76-88-51-09 (fax)
------------------------------------------------------------
Title: Multiwalled-carbon nanotubes as non-ballistic conductors
Authors: F. Triozon(1), A. Rubio(2), D. Mayou(2) and S. Roche(3)DRFMC/SPSMS, CEA Grenoble FRANCE
Affiliations: (1): LEPES/CNRS France (2)DIPC,CSIC-UPV/EHU, SPAIN (3) CEA, DRFMC/SPSMS, France
Abstract:
Intrinsic geometry of multi-walled carbon nanotubes allows to differentiate between long-ballistic, anomalous and diffusive-like conductors. Specific length scaling of the electronic conductance and temperature dependence of inelastic scattering times and conductivities in the weak electron-electron regime are predicted.
Dr. Stephan Roche
Commissariat a l'Energie Atomique, DRFMC/SPSMS
17 rue des Martyrs
Grenoble, 38054
FRANCE
33-4-76-88-33-81 (phone)
33-4-76-88-51-09 (fax)
------------------------------------------------------------
Title: Quantum interferences in carbon nanotubes
Authors: F. Triozon, A. Rubio and S. Roche
Affiliations: (1): LEPES/CNRS France (2)DIPC,CSIC-UPV/EHU, SPAIN (3) CEA, DRFMC/SPSMS, France
Abstract:
The role of backscattering is scrutinized in doped semiconducting carbon nanotubes and in multi-wallled tubules. By computing the participation ratio in several systems, the quantum correction to the Bloch-Boltzmann conductivity together with localization charateristics are shown to strongly depend on the position of the chemical potential.
Dr. Joerg Appenzeller
IBM Research Devision
T.J. Watson Research Center
Yorktown Heights, NY 10598
USA
914-945-3782 (phone)
914-945-4531 (fax)
------------------------------------------------------------
Title: A study on the electrical transport in and between single-wall carbon nanotubes
Authors: J. Appenzeller (*), H. Stahl (+), B. Lengeler (+), R. Martel (*), Ph. Avouris (*)
Affiliations: (*) IBM T.J. Watson Research Center, Yorktown Heights, NY 10598, (+) 2.Physikalisches Institut, RWTH Aachen, 52056 Aachen, Germany
Abstract:
By intentionally damaging ropes of single-wall carbon nanotubes through a controlled Ar-sputter treatment, we are able to characterize the electrical coupling between metallic nanotubes and to study coherent transport within metallic tubes with respect to the dominant phase breaking scattering mechanisms. Introducing sputter-damage to nanotubes in a rope, while preserving their structural integrity, enables to influence the current path through a rope as a function of temperature - meaning that at low enough temperatures current switches from one metallic tube to another one. Studying and modeling this process in detail is a possibility to thoroughly characterize the intertube barriers as well as the coupling mechanism between tubes in a rope. Our observations clearly proof that direct tunneling through a 250meV barrier posed by the semiconducting tubes in the rope is the dominant coupling mechanism. In addition, our data allow to characterize phase coherent transport in metallic nanotubes and to identify electron-electron scattering as well as Thouless scattering as the two relevant scattering processes dominating the coherent transport between 4K and room-temperature.
Dr. Thomas Pichler
Inst. für Materialphysik der Universität Wien
Strudlhofg. 4
Wien, 01090
Austria
00431427751372 (phone)
00431427751375 (fax)
------------------------------------------------------------
Title: CHARGE TRANSFER IN POTASSIUM DOPED C60 PEAPODS FROM RESONANCE RAMAN SCATTERING
Authors: T. Pichler1,2, W. Plank1, A. Grüneis1, H. Kuzmany1, H. Kataura3, Y. Achiba4
Affiliations: 1 Institut für Materialphysik der Universität Wien, Strudlhofg. 4, A-01090 Wien
Abstract:
We report on recent resonance Raman and resistivity measurements on potassium intercalation compounds of mats of fullerene containing SWNT (C$_{60}$ peapods). In situ potassium intercalation results in an increased conductivity and a loss of the resonance enhancements of the modes of the SWNT due to a bleaching of the optical transitions. The radial breathing mode (RBM) of the doped SWNT is hardened and has only a small photon energy dependence. For the tangential modes the C$_{60}$ $A_g$ pinch mode has a well known frequency dependence on the charge transfer and on dimerization and polymerization. Following this relation for potassium intercalation of C$_{60}$ peapods at low doping the charge transfer is predominantly to the SWNT whereas for full intercalation also charge transfer to the encapsulated C$_{60}$ up to C$_{60}$$^{-6}$ is observed. Work is supported by the FWF projects P12924 and P14146 and the TMR Research Network 'FUNCARS' (HPRN-CT1999-00011) from the EU. T.P thanks the \"OAW for funding.
Dr. Masako Yudasaka
ICORP-JST
34 Miyukigaoka
Tsukuba, Ibarakai 305-8501
Japan
81-298-50-1190 (phone)
81-298-50-1366 (fax)
------------------------------------------------------------
Title: Gas adsorption property of single-wall carbon nanohorns
Authors: K. Murata, K. Kaneko, D. Kasuya, K. Takahashi, F. Kokai, M. Yudasaka, and S. Iijima
Affiliations: ICORP-JST(Tsukuba), (NEC Tsukuba), Chiba Univ.(Chiba), IRI(Kashiwa), Meijo Univ.(Nagoya), Japan
Abstract:
Single-wall carbon nanohorns formed from single graphene sheets construct aggregates that have a large surface area. Porosity characteristics of the aggregates are similar to those of activated carbons, but the SWNH material does not need the high temperature and/or chemical treatment to activate itself. The pore sizes of the SWNH aggregates are controllable by selecting the duration and temperature of treatment in oxygen atmosphere. Such an easy control of pore-sizes is impossible for the conventional activated carbon. The pore-size control enables selective adsorption/storage of gas molecules.
Dr. Masako Yudasaka
ICORP-JST
34 Miyukigaoka
Tsukuba-shi , Ibarakai 305-8501
Japan
81-298-50-1190 (phone)
81-298-50-1366 (fax)
------------------------------------------------------------
Title: Structure control of single-wall carbon nanotubes and single-wall carbon nanohorns by chemical method
Authors: M. Yudasaka, M. Zhang, A. Koshio, Y. Kasuya, D. Kasuya, F. Kokai, K. Takahashi, S. Iijima
Affiliations: ICORP-JST(Tsukuba), NEC (Tsukuba), IRI(Kashiwa), Meijo Univ.(Nagoya), Japan
Abstract:
Single-wall carbon nanotubes (SWNTs) are micrometer-long fibrous tubes which usually form ropes, while the single-wall carbon nanohorns (SWNHs) are about 50-nm long forming spherical aggregates with diameters of about 80 to 100 nm. Both materials are formed from single graphene sheets. Structure and properties of SWNTs and SWNHs are changed by chemical reaction with organic materials, which are confirmed by thermogravimetric analyses, TEM, and spectroscopic method. The effect of structure change on the electromagnetic properties will be discussed.
Prof. Michael S Fuhrer
University of Maryland
Dept. of Physics
University of Maryland
College Park, MD 20742-4111
USA
301-405-6143 (phone)
301-304-9525 (fax)
------------------------------------------------------------
Title: Electronic transport in ultra-clean single-walled carbon nanotubes
Authors: M. S. Fuhrer^{1}, A. Bachtold^{2}, M. Forero^{2}, A. Zettl^{2}, Paul L. McEuen^{2}
Affiliations: ^{1} Dept. of Physics, University of Maryland, College Park, MD 20742 USA ^{2} Dept. of Physics, University of California at Berkeley and Lawrence Berkeley National Laboratory, Berkeley CA, 94720 USA
Abstract:
Devices consisting of individual CVD-grown carbon nanotubes up to ten microns long contacted by gold electrodes have been fabricated. By using electrostatic force microscopy to image the local potential in current-carrying devices, the mean free path in both semiconducting and metallic nanotubes has been measured. Individual scattering sites in semiconducting nanotubes can also be studied by monitoring the nanotube conductance while using the AFM tip as a local gate. CVD-grown nanotubes are exceptionally free of disorder: room temperature mean free paths of up to 700nm are possible in CVD-grown semiconducting nanotubes. Low temperature transport measurements indicate that the mean free path in semiconducting nanotubes may be as long as 6 microns. Results on these semiconductor quantum dots will also be discussed. A new electrically-programmable memory device based on a single semiconducting nanotube will also be presented.
Dr. Yoshiyuki Miyamoto
Fundamental Research Labs., NEC Corp.
34 Miyukigaoka
Tsukuba, Ibaraki 305-8501
Japan
+81-298-50-1586 (phone)
+81-298-50-2647 (fax)
------------------------------------------------------------
Title: Interwall interaction and charge redistribution in double-wall carbon nanotubes
Authors: Yoshiyuki Miyamoto, Susumu Saito, and David Tomanek
Affiliations: Fundamental Research Labs., System Devices and Fundamental Research, NEC Corporation; Department of Physics, Tokyo Institute of Technology; Department of Physics and Astronomy, Michigan State University
Abstract:
Double-wall carbon nanotubes (DWCNTs) are attracting increasing interest due to their spontaneous formation from single-wall nanotubes filled with fullerenes under electron irradiation. Early theoretical studies have focused on the stability [1] and electronic structure [2] of selected DWCNTs. Here we report the first theoretical study of the charge distribution and electronic potential profiles of DWCNTs. Our self-consistent density functional calculations indicate a significant charge redistribution in nanotubes sandwiched in-between graphene sheets, and in double-wall nanotubes. We find the net charge transfer to involve not only pi-electrons in the system, but more importantly a new inter-wall state, which is reminiscent of the interlayer state of graphite [3]. Our results elucidate the charge transfer trends and the common origin of the inter-wall and inter-layer states. We also discuss how the modified charge density near the Fermi level affects Scanning Tunneling Microscopy images and the conductivity of multi-wall nanotubes. This work was performed under the management of Frontier Carbon Technology supported by NEDO. [1] J.-C. Charlier and J.-P. Michenaud, Phys. Rev. Lett. 70, 1858 (1993). [2] Y. K. Kwon and D. Tom\'anek, Phys. Rev. B58, R16001 (1998). [3] N.A.W. Holzwarth, S.G. Louie, and S. Rabii, Phys. Rev. B26, 5382 (1982), and references therein.
Prof. Susumu Saito
Tokyo Institute of Technology, Department of Physics
2-12-1 Oh-okayama
Meguro-ku
Tokyo, 152-8551
Japan
+81-3-5734-2070 (phone)
+81-3-5734-2739 (fax)
------------------------------------------------------------
Title: Boron Nanotubes: A Theoretical Study
Authors: Susumu Saito and Koichiro Umemoto
Affiliations: Department of Physics, Tokyo Institute of Technology
Abstract:
A hexagonal layer of boron is now of high interest due to superconductivity with high transition temperature observed in MgB2 in which boron atoms form graphitic layers. Accordingly, a formation of nanotubes from boron atoms is an interesting issue to be studied in detail. We will discuss the energetics and the electronic properties of boron nanotubes studied in the framework of the density-functional theory.
Prof. jisoon Ihm
Seoul National Univ.
School of Physics
Seoul, 151-742
Korea
82-2-880-6614 (phone)
82-2-884-3002 (fax)
------------------------------------------------------------
Title: Field-dependent secondary electron emission from MgO-deposited carbon nanotubes
Authors: Jisoon Ihm, Youngmi Cho and Gunn Kim
Affiliations: Seoul National University
Abstract:
A highly enhanced secondary electron emission from MgO-deposited carbon nanotubes under a large bias voltage has been found recently by a collaborating experimental group and its underlying mechanism is investigated in the present work. We propose a self-consistent semi-classical model based on a major redistribution of charge to explain a huge amount of secondary electrons and their energy distribution which deviate from the standard theory of secondary electron emission. We analyze the effects of the primary electron energy, bias voltage, and the thickness of MgO on the yield of secondary electrons, and they are compared with the experimental data. Ab initio pseudopotential electronic structure calculations are also performed for the MgO-deposited tubes to help clarify the basic mechanism. Critical factors for a large yield of emission and their significance to practical applications will be discussed.

B - Accepted contributions.

Dr. Jean-Louis M. Sauvajol
GDPC
Université Montpellier II
Place E. Bataillon, CC 026
Montpellier Cedex 5, 34095
France
(33) 4 67 14 35 92 (phone)
(33) 4 67 14 46 37 (fax)
------------------------------------------------------------
Title: A neutron scattering investigation of the pressure-induced structural changes and low frequency excitations in SWNT bundles.
Authors: J. L. Sauvajol, S. Rols and R. Almairac
Affiliations: Université Montpellier II
Abstract:
In a first part we investigate the pressure-induced structural changes of single-wall carbon nanotubes organised into 2D crystalline bundles by neutron diffraction up to 50 kbars. The pressure dependence of the position of the (10) Bragg peak is found to depend on the orientation of the axis of the anvil cell with respect to the diffraction plane. This behavior implies the presence of an uniaxial pressure component along the axis of the anvil cell. The pressure dependence is well described in the framework of a pressure-induced progressive deformation of the tubes section, from circular to hexagonal, in addition of the van der Waals compression. In a second part we present recent inelastic neutron scattering measurements of the vibrational density of states (VDOS) of single wall carbon nanotubes, by focusing in the low frequency range (E<12 meV). We report the first unambiguously evidence of low frequency excitations assigned to libration and twist modes of tube in bundles. A linear dependence of the VDOS in the range 0-1.5 meV was systematically observed in neutron experiments for SWNT samples prepared with various techniques. We discuss the main features of this density of states in the light of calculations using a force constant model including interactions up to the fourth neighbor in the tube and considering a van der Waals interaction between the tubes.
Ms. Steffi Friedrichs
Inorganic Chemistry Laboratory
University of Oxford
South Parks Road
Oxford, Oxfordshire OX1 3QR
United Kingdom
+44-1865-272640 (phone)
+44-1865-272690 (fax)
------------------------------------------------------------
Title: Simultaneous determination of inclusion crystallography and nanotube conformation for a Sb2O3:SWNT composite
Authors: S. Friedrichs, R.R. Meyer, J. Sloan, A.I. Kirkland, J.L. Hutchison, M.L.H. Green
Affiliations: Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR U.K., Department of Materials Science, Pembroke Street, Cambridge, CB2 3QZ, U.K.
Abstract:
The detailed inclusion crystallography of a 1-dimensional valentinite Sb2O3 crystal incorporated within a helical (21,-8) single walled carbon nanotube has been identified from a phase image that was recovered via a modified object wave restoration scheme. A detailed analysis of asymmetric fringe contrast in the tube walls has provided strong evidence for the chiral sense of the tube itself. Due to the good agreement of observed wall periodicity with the determined absolute focus values and power spectra obtained from single-pixel line traces along both tube walls, we were able to determine the chiral sense of the SWNT and the tilt angle of the Sb2O3/SWNT composite relative to the electron beam. The angle between the optimum <1 0 –1> viewing direction of the crystal fraction and the tube axis, which is aligned with the <4 –1 2> direction of the Sb2O3 crystal, is 78.3°. Since small deviations from this viewing direction make an insignificant difference to the observed contrast, a tube inclination of 15° is plausible for both the Sb2O3 crystal and the assigned (21,-8) SWNT, which is the mirror image of a (13,8) SWNT.
Ms. Susana Trasobares
Laboratoire de Physisques des Solides
Universite Paris Sud
Bat. 510
Orsay, 91405
France
0033 169156076 (phone)
0033 169158004 (fax)
------------------------------------------------------------
Title: Electron beam identification and machining of novel hybrid nanotubular structures
Authors: Trasobares S. Stephan O. C. Colliex, G. Hug*, W.K.Hsu+, H.W.Kroto+, D.R.M. Walton+
Affiliations: LPS, Universite Paris Sud, Bat 510, 91405 Orsay, France. * ONERA-LEM, 92322 Chatillon Cedex, France. + CPES University of Sussex, Brighton BN1 9QJ, England.
Abstract:
Nowadays can be considered as the nanotechnology era where materials at the nanometer scale (e.g. nanotubes), which present high potential properties, are being produced and investigated. The hollow structure of the nanotubes can be used as moulds for creating new nanostructures (e.g. nanowires), to encapsulate molecules as C60 or C82@Gd and to store gas. The carbon nanotubes also can be doped with different elements as halides, B/N, to produce batteries or to get new nanodevices. However the identification of such complex B-C-N structures or SWNT@C82@Gd requires accurate nanometre-scale analysis which is available in high-resolution imaging and electron microscpe. Carbon nanotubes containing nitrogen and nanocapsules regularly distributed along the tube axis, have been produced by pyrolysing camphor in the presence of nitrogen and ammonia. Spatially resolved electron energy-loss spectroscopic (EELS) analysis reveals that N2 gas is encapsulated within the nanocapsules. The well-graphitized walls can be punctured by electron irradiation, thus partly releasing N2, accompanied by the formation of amorphous CNx island, as demonstrated by dynamic recording and analysis of time-resolved EELS sequences. Such local in-situ electron beam nanomachining and nanoanalysis provide a method for creating new classes of nanodevices.
Dr. Alexander V. Okotrub
Institute of Inorganic Chemistry SB RAS
pr. Ak. Lavrent'eva, 3
Novosibirsk, 630090
Russia
+7(3832) 341366 (phone)
+7(3832)344489 (fax)
------------------------------------------------------------
Title: Fluorinated single-wall carbon nanotubes
Authors: A.V. Okotrub, N.F. Yudanov, L.G. Bulusheva, A.I. Romanenko
Affiliations: Institute of Inorganic Chemistry SB RAS, pr. Ak. Lavrent’eva 3, Novosibirsk 630090, Russia
Abstract:
Single-wall carbon nanotubes (SWNTs) were synthesized by co-evaporation of graphite and cobalt-nickel ultra-disperse power during arc-discharge process. The content of SWNTs in the soot collected on a nickel screen was estimated from transmission electron microscopy (TEM) to be about 20%. The nanotube-contained material was fluorinated at room temperature using a volatile BrF_3. The elemental composition of sample produced was determined using X-ray photoelectron spectroscopy (XPS) to correspond to CF_0.1. Taking account that the soot is not fluorinated at applied synthetic condition and the tube content in the sample, the SWNTs are fluorinated up to C_2F composition. TEM showed that upon the fluorination the SWNT ropes are split into the individual tubes. Treatment of the product by hydrazine allows removing the fluorine. Conductivity of pristine, fluorinated, and defluorinated materials was measured by four-point technique. Fluorination lowers the room temperature conductivity of the samples more than in 10^4. The temperature behavior of conductivity for the fluorinated SWNTs was found to differ from that in the pristine material and to be characteristic of narrow-gap semiconductors. The defluorinated sample showed the increase of electron emission in the low-voltage region of I-V dependence compared to the pristine SWNTs.
Mr. Xianjie Liu
IFW Dresden, Institute for Solid State Research
Helmholtzstr. 20, D-01069, Dresden
Dresden, D-01069
Germany
(phone)
+49 (351) 4659 440 (fax)
------------------------------------------------------------
Title: Electronic structure of pristine, fullerene-filled and intercalated SWCNT from high resolution EELS in transmission
Authors: X. Liu^{1}, T. Pichler^{1,2}, M. Knupfer^{1}, M. S. Golden^{1}, J. Fink^{1}, D. Walters^{3}, M. J. Bronikowski^{3}, R. E. Smalley^{3}, and H. Kataura^{4}
Affiliations: ^{1} IFW Dresden, Institute for Solid State Research, PO Box 270016, D-01171 Dresden, Germany, ^{2} Institut f\"ur Materialphysik, Universit\"at Wien, A-1090 Wien, Austria, ^{3} CNST, Rice University, Texas, USA, ^{4} Department of Physics, Tokyo Metropolitan University, Japan
Abstract:
We present recent studies of the electronic structure and optical properties of SWCNT using high resolution electron energy-loss spectroscopy (EELS) in transmission. Firstly, we report the role of the SWCNT diameter upon the basis of data from SWCNT with mean diameters ranging from 0.8-1.4nm. We then discuss the effects brought about by doping these systems, either endohedrally with C_{60} molecules (forming so-called peapods) or exohedrally with alkali metals (n-type doping) or FeCl_{3} (p-type doping).
Dr. Anatoly I Romanenko
Institute of Inorganic Chemistry Siberian Branch of RAS
Ac. Lavrentyev Ave., 3, Novosibirsk, Russia, 630090
Novosibirsk, 630090
Russia
(7-3832) 342531 (phone)
(7-3832) 344489 (fax)
------------------------------------------------------------
Title: Transport and magnetic properties of brominated multiwall carbon nanotubes
Authors: A.I. Romanenko^{1,2}, A.V. Okotrub^{1}, Cheng DONG^{2}, Yongming NI^{2}, O.B. Anikeeva^{1}, L.G. Buluseva^{1}, N.F. Yudanov^{1}
Affiliations: Institute of Inorganic Chemistry Siberian Branch of Rassian Academy of Sciences^{1}, National Laboratory for Superconductivity, Institute of Physics Chinese Academy of Science, Beijing, China^{2}
Abstract:
Laminated carbonaceous material composed of multiwall carbon nanotubes has been prepared by arc discharge graphite evaporation in helium atmosphere. Scanning electron microscopy showed that the inner part of carbon deposit grown on the cathode consists of tubular particles mainly. The tubes were estimated by transmission electron microscopy to have from 2 to 30 shells with outer diameter of 60-150 {\AA }. The brominated material was prepared by exposure of the pristine one to $Br_2$ vapors. Its composition was determined by x-ray photoelectron spectroscopy to be $CBr_{0.06}$. The magnetoconductivity, magnetic susceptibility and temperature dependence of conductivity of pristine and brominated samples were investigated. The pristine sample was found to characterize by conductivity anisotropy $10^2$, which disappears after sample bromination. The positive magnetoconductivity and additional contribution to magnetic susceptibility of the pristine material and the brominated material was observed. The extrinsic conduction carrier concentration $n_0$ for the pristine sample and brominated that was estimated in the framework of the quasi-two-dimensional graphite band model by the method of Kotosonov using the fitting parameters of diamagnetic susceptibility. Really, the value of $n_0$ for brominated sample increases in comparison to that for pristine sample from $3\times 10^{10}$ to $10^{11}$ $cm^{-2}$.
select. Young Hee Lee
Sungkyunkwan University
Department of Physics, Sungkyunkwan University,
Suwon, Kyungki 440-746
R. O. Korea
82-31-290-7040 (phone)
(fax)
------------------------------------------------------------
Title: Application of carbon nanotubes to energy storages
Authors: Y. H. Lee, K. H. An, W. S. Kim, K. G. Jeon, Y. S. Park, J. M. Moon
Affiliations: Department of Physics, Sungkyunkwan University
Abstract:
Carbon nanotubes have been intensively investigated for their fundamental and technical importances. Several issues for the applications to energy storage of hydrogen storage, secondary battery, supercapacitors will be discussed. Hydrogen storage using hydrostatic pressure and electrochemical approaches with carbon nanotubes are currently on debate. The maximum storage capacity reported so far varies from group to group. We will demonstrate that the storage capacity is strongly dependent on the sample-preparation conditions. The stability, flatness on the voltage scan, and cycle life will be extensively discussed. On the other hand, the supercapacitor with non-fadadaic reaction has long cycle life and high power density but low energy density. Therefore development of a supercapacitor with high energy density is always desirable. We demonstrated already a maximum capacitance of 180 F/g and a measured power density of 20 KW/kg and an energy density of 7 Wh/kg in a solution of 7.5 N KOH using singlewalled carbon nanotubes[1]. These values are still lower than that of commercially available activated carbons. We will report our effort to improve the energy density using various nanotube-polymer composites.
Prof. Sergey A. Maksimenko
Institute for Nuclear Problems
11 Bobruiskaya Str.,
Minsk, 220050
Belarus
375 172 26 42 20 (phone)
375 172 26 51 24 (fax)
------------------------------------------------------------
Title: Linear electrodynamics of carbon nanotubes
Authors: S.A. Maksimenko^{1}, G.Ya. Slepyan^{1}, A. Lakhtakia^{2}, and O.M. Yevtushenko^{3}
Affiliations: ^{1} Institute for Nuclear Problems, Belarus State University, Bobruiskaya str. 11, Minsk, 220050, Belarus, ^{2} Department Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802--6812, USA, ^{3} Institute for Radiophysics and Electronics, Ak. Proskura str. 12, Kharkov, 310085, Ukraine
Abstract:
Electronic and electromagnetic properties of carbon nanotubes (CNs) are considered in the microwave, the infrared and the visible regimes. Contribution comprises our recent results on linear electrodynamics of CNs [1-3]. Microscopic consideration of a CN's conductivity is undertaken both in the semi--classical approximation and on the basis of a rigorous quantum--mechanical model. Analytical expressions for the dynamic conductivity are derived and numerical results for different types of CNs are presented. Effective boundary conditions for the electromagnetic field and the electrostatic potential in CNs are stated on the nanotube surface providing thereby the most appropriate tool for solving electrodynamic problems involving CNs. The existence of surface TM--waves is pointed out and frequency ranges are shown to exist wherein these waves can propagate to distances essentially exceeding the CN length. That allows the concept of nanotubes as nanowaveguides. A composite medium comprising electrically small CNs dispersed in some host material is also considered. A homogenization procedure for such composites and some optical properties of them are discussed. [1] A. Lakhtakia, et al., Carbon 36, 1833 (1998). [2] G. Ya. Slepyan, et al., Phys. Rev. B57, 9485 (1998); B60, 17136 (1999). [3] S. A. Maksimenko and G. Ya. Slepyan, in "Electromagnetic Fields in Unconventional Structures and Materials", Ed. by: O.N. Singh and A.Lakhtakia, Wiley \& Sons, New York 2000, pp. 217-255.
Prof. Gregory Ya. Slepyan
Institute for Nuclear Problems
11, Bobryiskaya str.
---
Minsk, --- 220050
Belarus
375 172 26 42 20 (phone)
375 172 26 51 24 (fax)
------------------------------------------------------------
Title: Nonlinear optics of intense ultrashort light pulses in carbon nanotubes
Authors: G.Ya. Slepyan^{1}, A.A. Khrushchinskii^{1}, S.A. Maksimenko^{1}, V.P. Kalosha^{1}, and J. Herrmann^{2}
Affiliations: ^{1} Institute for Nuclear Problems, Belarus State University, Bobruiskaya 11 Str., 220050 Minsk, Belarus, ^{2} Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Str. 2a, D-12489 Berlin, Germany
Abstract:
Carbon nanotubes (CNs) are characterized by strong nonlinearities which are yet not completely understood. The nonlinear optical properties make CNs attractive for different applications and are expected to provide useful information on the dynamics of electron motion in CNs. In particular the pronounced electronic nonlinearity in CNs could represent a useful mechanism for the generation of very short wave-lengths by high-order harmonic generation (HHG) in a device confined to a very small sub-mm region. In our contribution we present a quantum-mechanical theory of the nonlinear optical properties of CNs exposed to an intense ultrashort pulse. The theory takes into account the effect of interband transitions of p-electrons and utilizes a direct analysis in the time domain. We predict the current density harmonic spectrum as a set of discrete lines imposed by incoherent continuous background. Further we study the characteristic features of the third and fifth harmonics as well as of the harmonics of very high orders in metallic and semiconductor CNs and demonstrate a new cutoff mechanism for HHG. The results of the rigorous quantum-mechanical theory are compared with that of our previous semiclassical theory [1]. [1] G. Ya. Slepyan, et al., Phys. Rev. A61 R777 (1999); Phys. Rev. A63 (2001, accepted)
Prof. Gotthard Seifert
Theoretische Physik, Universitaet Paderborn
Warburger Str. 100
Paderborn, 33095
Germany
+49 5251-60-2331 (phone)
+49 5251-60-3435 (fax)
------------------------------------------------------------
Title: On the Stability and Formation of Nanotubes
Authors: G. Seifert
Affiliations: Universitaet -Paderborn
Abstract:
On the basis of Density-Functional based tight-binding calculations a model explaining the stability pf single-wall and multi-wall carbon and non-carbon nanotubes is derived. The energetic competition between single-layer and multilayer sheets the corresponding single wall and multi-wall nanotubes is discussed. It is demonstrated how the energetics of a contious bending of flat sheets to tubular structures may serve as a possible path to the tube formation. Finally, it is shown how the bending barrier may be reduced by the presence of transition metals, as catalysts for tube formation.
Dr. Oliver Jost
TU Dresden
Hallwachsstrasse 3
Dresden, 01069
Germany
+49-351-463-1425 (phone)
+49-351-463-1422 (fax)
------------------------------------------------------------
Title: Optical absorption study of rate-limiting processes in the laser evaporation synthesis of single-wall carbon nanotubes
Authors: O. Jost^{1}, A.A. Gorbunov^{1}, W. Pompe^{1}, X. Liu^{2}, M.S. Golden^{2}, and J. Fink^{2}
Affiliations: ^{1} Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, ^{2} Institute for Solid State Research, IFW Dresden, D-01171 Dresden, Germany
Abstract:
Optical absorption spectroscopy is known to offer an express, bulk-sensitive measure of the relative single-wall carbon nanotube (SWCNT) yield in as-produced material [1,2]. Consequently, we performed a systematic study of synthesis parameters in the furnace-based laser evaporation synthesis of SWCNT including variations of the gas-type, gas-pressure and furnace temperature. In our contribution, we present selected results dealing with the determination of a number of rate-limiting processes. A total of four such rate-limiting processes could be found, two of them being not only rate-limiting but covering all the relevant gas-type and gas-pressure dependencies of the SWCNT formation. Two condensed-state-based thermally activated processes with their activation energies could also be determined. The results allow the derivation of a self-consistent flow-chart describing the proccesses taking place in the formation of SWCNT. This work was supported in part by the DFG (PO392/10-2 & FI439/8-2) and the EC (FET-NID initiative, project IST-10593-SATURN). [1] O. Jost et al., Appl. Phys. Lett. 75, 2217 (1999) [2] O. Jost et al., Chem. Phys. Lett., in press
Dr. Alf Mews
Physical Chemistry
University of Mainz
Welderweg 11
Mainz, 55099
Germany
06131 392 2982 (phone)
06131 392 3953 (fax)
------------------------------------------------------------
Title: Raman imaging of chemically modified individual Carbon Nanotubes
Authors: A. Mews^{1}, C. Jiang^{1}, T. Schuessler^{1}, F. Koberling^{1}, T. Basché^{1}, G. Philipp^{2},M. Burghard^{2}
Affiliations: ^{1}Physical Chemistry, University of Mainz, Germany, 55099 Mainz, ^{2}Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, 70569 Stuttgart (Germany)
Abstract:
In this paper we will show that scanning confocal Raman microscopy can be used as an analytic tool to localize and investigate individual tubes and detect their vibrational modes with sub-mm lateral resolution. In particular, we present a detailed correlation of spectroscopic investigations and the geometry of thin bundles and individual single-wall CNTs using scanning confocal Raman microscopy and scanning force microscopy. By using different excitation wavelength it is possible to mainly address the metallic or semiconducting tubes within a given bundle. Also, this approach allows to compare the Raman signals from chemically modified and unmodified CNTs. By subsequent deposition of oxidized and unoxidized CNTs, the different species can be clearly distinguished from one another and the effect of the oxidation upon the electronic structure can be investigated in detail.
Dr. Burkhard Renker
Forschungszentrum Karlsruhe, IFP
Postfach: 3640
76021 Karlsruhe, D-76021
Germany
07247-82-2706 (phone)
07247-82- 4624 (fax)
------------------------------------------------------------
Title: Hydrogen storage in carbon nanotubes: A neutron scattering investigation
Authors: B. Renker (1), S. Lebedkin (2), H. Schober (3), M. Koza (4), M.M. Kappes (5)
Affiliations: 1)Forschungszentrum Karlsruhe, IFP, D-76021 Karlsruhe, 2) Forschungszentrum Karlsruhe, INT, D-76021 Karlsruhe, Germany, 3) TU-München, Phys. Dep. E13, D-85747 Garching, Germany, 4) Inst. Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9, France, 5) Inst. Phys. Chem. II, UNI Karlsruhe, D-76128 Karlsruhe, Germany
Abstract:
Carbon single-walled nanotubes (SWNTs) were prepared by pulsed laser vaporization and cleaned by annealing in dynamic vacuum. Both, as prepared material consisting of closed SWNTs and chemically treated material consisting of opened SWNTs were charged with hydrogen gas at 180 bar. Inelastic Neutron scattering data including raw spectra, the phonon density of states and the dynamical susceptibility (quasielastic component) will be presented for different temperatures between 150 K and 400 K. Clear evidence is obtained for larger amounts of H2 adsorbed inside the SWNTs giving rise to a well pronounced inelastic scattering spectrum which reaches up to »250 meV. Most of the weakly bond H2 desorbs rapidly near 300 K however, tightly bond hydrogen is still observed at higher energies and 400 K. Structural information on both kinds of materials as obtained from elastic and quasielastic scattering contributions will be discussed. By a comparison to a Vanadium standard we can quantify our results.
Dr. Liu Yang
NASA Ames Research Center
Mail-stop 230-3
Moffett Field, CA 94035
US
650-604-5408 (phone)
(fax)
------------------------------------------------------------
Title: Electronic and Mechanical Properties of Hydrogen Functionalized Carbon Nanotubes
Authors: Liu Yang, Richard Jaffe, Jie Han
Affiliations: NASA Ames Research Center
Abstract:
We examined the electronic and mechanical properties of hydrogen functionalized carbon nanotubes. The functionalization pattern covers two extreme groups. One group has randomly selected functionalization sites including one to twenty percent of the carbon atoms. The other group has regularly patterned functional sites parallel to the tube axis. Metallic, small-gap semiconducting and large-gap semiconducting carbon nanotubes are studied. The results reveal that the electronic properties of the tubes are very sensitive to the degree of functionalization, with even one percent functionalization being enough to render metallic tubes semiconducting. On the other hand, the mechanical properties, like tensile modulus, are much less sensitive to functionalization. For carbon nanotubes functionalized with specific patterns, the electric properties depends strongly on the nature of the functionalization pattern.
Prof. ALDO D MIGONE
SOUTHERN ILLINOIS UNIVERSITY AT CARBONDALE
DEPARTMENT OF PHYSICS
NECKERS BUILDING RM # 483
CARBONDALE, IL 62901
USA
618-453-1053 (phone)
618-453-1056 (fax)
------------------------------------------------------------
Title: Xenon adsorption on the outer surface of closed ended SWNT bundles
Authors: S.Talapatra,N.Dolan and A.D.Migone
Affiliations: Department of Physics, Southern Illinois University at Carbondale
Abstract:
Adsorption isotherms of Xenon on closed ended SWNT were measured in order to determine the adsorption behavior of this gas on the outer surface of the bundles. We will present monolayer adsorption data measured at various temperatures on nanotube samples from two different sources. The pressures at which Xe adsorption occurs on the highest binding energy sites on the SWNT's are lower than those for Xe on planar graphite,indicating that the binding energies for Xe are higher on the SWNT's.We will also present preliminary results for argon adsorption measurements on SWNT's.The Ar and the Xe results will be compared to each other and to results of computer simulations for these gases.
Prof. ALDO D MIGONE
SOUTHERN ILLINOIS UNIVERSITY AT CARBONDALE
DEPARTMENT OF PHYSICS
NECKERS BUILDING RM#483
CARBONDALE, IL 62901
USA
618-453-1053 (phone)
618-453-1056 (fax)
------------------------------------------------------------
Title: Adsorption studies of Xenon on carbon nanohorns
Authors: A.J.Zambano,W.Mcmillin,S.talapatra,G.Shaugnessey and A.D.migone
Affiliations: Department of Physics, Southern Illinois University at Carbondale, IL-62901,USA
Abstract:
Adsorption isotherm measurements were performed on recently discovered nano-aggregates of graphitic nano horns (SWNH). The data suggests that there are two different groups of adsorption sites present in the substrate. The energy of the highest binding site was determined from low coverage adsorption isotherm data by calculating the isosteric heat of adsorption for nine (190 K – 305 K) different temperatures. The binding energy for these higher energy sites is 48% greater than that for Xe on planar graphite and 15% smaller than that of closed ended single walled carbon nanotubes (SWNT). Results of full isotherms, measured to determine the monolayer capacity of Xenon on SWNH sample, will also be presented.
Dr. Takeshi Nakanishi
Delft University of Technology
Department of Applied Physics
Lorentzweg 1
Delft, 2628 CJ
The Netherlands
+31-15-278-6154 (phone)
+31-15-278-1203 (fax)
------------------------------------------------------------
Title: Wave-Vector Conservation and Electric Transport through Crossed Carbon Nanotube
Authors: Takeshi Nakanishi^{1} and Tsuneya Ando^{2}
Affiliations: ^{1}Delft Univ. of Technology, ^{2}ISSP Univ. of Tokyo
Abstract:
Carbon nanotubes (CNs) are new kinds of quantum wires with particular transport properties. A junction of two crossed nanotubes is likely to be a fundamental element to form multiterminal molecular devices using CNs. The purpose of this paper is to study electric transport through crossed single-wall CNs and to demonstrate the importance of wave-vector as well as energy conservation. An effective-mass scheme has been used successfully in the study of wide varieties of electronic properties of CNs including transport properties. In this paper the effective-mass scheme is extended to junctions of crossed CNs and an effective Hamiltonian describing their coupling is derived. For a realistic model, it turns out that effective coupling between two tubes is reduced considerably due to interferences of couplings between different atoms except when hexagons on two CNs stack in a commensurate way. As a result dominant components of the effective couplings take sharp and high peaks as a function of the angle between the tubes. The conductance between two metallic armchair CNs is calculated and shown to have a sharp maximum at the peaks of the dominant components and be negligibly small except for these peaks.
Prof. Chakram S Jayanthi
University of Louisville
Department of Physics
Louisville, Kentucky 40292
USA
502-852-1134 (phone)
502-852-0742 (fax)
------------------------------------------------------------
Title: Structural and Electronic Properties of a Carbon Nanotorus: Effects of Extended Vs Local Deformations
Authors: S.Y. Wu, L. Liu, and C.S. Jayanthi
Affiliations: Department of Physics, University of Louisville
Abstract:
To study the effects of bending of a carbon nanotube, we consider a carbon nanotube bent into a ring and follow the deformation of a carbon nanotorus through various stages, namely, from elastic deformation to the onset of the kinks and eventually to the collapse of the walls of the nanotorus. The changes in the electronic properties due to extended deformations are contrasted with those due to local deformations to bring out the subtle issue underlying the reason why there is only a relatively small reduction in the electrical conductance in the former case even at larger bending angles while there is a dramatic reduction in the conductance in the latter case at relatively small bending angles.
Prof. Chakram S. Jayanthi
University of Louisville
Department of Physics
Natural Sciences Building
Louisville, Kentucky 40292
USA
502-852-1134 (phone)
502-852-0742 (fax)
------------------------------------------------------------
Title: Broken Symmetry, Boundary Conditions, and Band Gap Oscillations in Finite Single-Wall Carbon Nanotubes
Authors: C.S. Jayanthi, L. Liu, and S. Y. Wu
Affiliations: University of Lousiville
Abstract:
The interplay between the broken symmetry and the boundary conditions alters profoundly the electronic properties of carbon single-wall (SW) nanotubes (NTs) of finite-lengths. For NTs $(p,q)$ characterized by $p=k+l$, $q=k-l$, $0 \le l\le k$, and $k=1,2,\cdots$, the HOMO-LUMO gaps for finite SWNTs belonging to a given family $k$ exhibit strikingly similar oscillating patterns (when plotted in terms of {\it even} NT sections) with diminishing amplitudes from the armchair, to chiral, and to the zigzag SWNTs. However, in terms of the NT length, the gap maximum repeat at different periodicities for different SWNTs. We find that ASWNT at selected lengths behave as semiconductors, in contrast to the metallic behavior of infinite ASWNTs. On the other hand, infinite ZSWNTs which can be either metallic or semiconducting behave as molecular-scale conductors. These results are expected to have profound implications in the utilization of finite-length CNTs as molecular-scale devices.
select. Jean-Louis Sauvajol
G.D.P.C.
Université Montpellier II
Place E. Bataillon, cc26
Montpellier cedex 5, 34095
France
(33) 4 67 14 35 92 (phone)
(33) 4 67 14 46 37 (fax)
------------------------------------------------------------
Title: Raman studies of alkali-doping of SWNT
Authors: J.-L. Sauvajol, N. Bendiab, A. Zahab, E. Anglaret,
Affiliations: G.D.P.C, Université Montpellier II
Abstract:
Phase transitions and staging in intercalated single wall carbon nanotubes (SWNT) are controversial issues. In this communication, we report on combined in situ conductivity and Raman measurements of Rb doping of SWNT. Concomitant decrease of the resistance and change in the Raman spectrum are evidenced upon doping. In the last steps of doping, two distinct Raman spectra are observed and assigned to the Raman signatures of two different doped phases. These results are compared with Raman spectra recorded on SWNT sample doped with various alkali metals (Cs, Li, Na) at different and controled stoichiometries. All these results are discussed in terms of charge transfer and structural organisation in SWNT- alkali system. An unified interpretation of the whole results is proposed.
Dr. Frank Rohmund
School of Physics and Engineering Physics
Gothenburg University and Chalmers University of Technology
Gothenburg, 412 96
Sweden
+46 31 772 3234 (phone)
+46 31 772 3496 (fax)
------------------------------------------------------------
Title: Growth and properties of CVD-grown carbon nanotube films
Authors: F. Rohmund, R.-E. Morjan, M. Sveningsson, O.A. Nerushev, A. Gromov, L.K.L. Falk, E.E.B. Campbell
Affiliations: School of Physics and Engineering Physics, Gothenburg University and Chalmers University of Technology, SE-412 96 Gothenburg, Sweden, e-mail: frankr@fy.chalmers.se
Abstract:
Films of carbon nanotubes are technologically interesting, for example as cold cathodes in field emission devices. We grow such films directly onto substrates by thermal chemical vapour deposition, employing the catalytic activity of iron particles which are produced in situ. Films of aligned and non-aligned carbon nanotubes can be synthesised, depending on growth conditions and on the type of carbon precursor molecule used. In this contribution we discuss the various nanotube film morphologies and nanotube structures which are obtained when hydrocarbon or fullerene molecules are used as carbon feedstock gases. Film characterisation is carried out by electron microscopy and Raman spectroscopy, and the correlation between these two methods is demonstrated. Our results show how the diameter distribution of the supported catalytic metal particles influences the formation of nanotubes and other carbon structures. We also perform field emission measurements on various as-grown nanotube films which enable us to correlate nanotube film structure information to field emission effiencies. The field emission process is accompanied by a strong light emission, which is spectrally analysed.
Mr. Anders Hansson
Department of Physics and Measurement Technology, IFM
Linköping University
Linköping, S-581 83
Sweden
+46 13 288962 (phone)
+46 13 132285 (fax)
------------------------------------------------------------
Title: Conductance of multi-wall carbon nanotubes
Authors: Anders Hansson, Magnus Paulsson, and Sven Stafström
Affiliations: Linköping University
Abstract:
The aim of this theoretical work is to find methods to control the current through multi-wall carbon nanotubes (MWNTs). In our model system the tight-binding approximation is used to describe a finite MWNT ((10,10)@(5,5)) connected to two semi-infinite metallic leads. The current-voltage characteristics is calculated from the multi-channel Landauer formula. Changes in the on-site energy, the interaction between layers of the MWNT and interaction with the leads are investigated to determine how they affect the conductance. In the experimental situation this corresponds to applying a gate voltage either to the underlying substrate or to a microscopy-tip. The interaction between the layers may also be increased by mechanically deforming the MWNT with the tip. In the case of weak interaction between the leads and MWNT the calculations show that the conductance mainly depends on the wavefunction amplitude on the sites connecting the MWNT to the leads. The elastic scattering induced by defects thus does not necessarily decrease the current through the MWNT. A device in which the leads are contacted to different coaxial layers of the MWNT (telescopic junction) is also investigated and the sensitivity to defects studied.
Prof. Cheol Jin Lee
Kunsan National University
San 68, Miryong-dong,
Kunsan, Chonbuk 573-701
Korea
82-63-469-4744 (phone)
82-63-469-4744 (fax)
------------------------------------------------------------
Title: Growth Mechanism of Bamboo-shaped Carbon Nanotubes using Thermal Chemical Vapor Deposition
Authors: C. J. Lee1, T. J. Lee1, S. C. Lyu 1, and J. E. Yoo2
Affiliations: 1 School of Electrical Engineering, Kunsan National University, Kunsan 573-701, Korea
Abstract:
Since the first observation of carbon nanotubes (CNTs), extensive researches have focused on the synthesis of CNTs with high purity. Various synthetic methods such as arc discharge, laser vaporization, pyrolysis, and plasma-enhanced and thermal chemical vapor deposition (CVD) were employed. Despite great progress in the growth of CNTs, the growth mechanism has still not been completely understood. Given the different synthetic techniques, it is likely that a variety of mechanisms play a role in the growth of CNTs. Two growth models, i. e. base growth and tip growth models, were proposed for the catalytic growth of carbon nanotubes. In this works, we found no encapsulated catalytic particles at the closed tip from the bamboo-shaped CNTs grown by thermal CVD of acetylene (C2H2) at temperatures range 750-950 ¨¬C. Moreover, CNTs have compartment curvatures toward the tip. Based on the experimental results, we suggest a base growth model for the bamboo-shaped CNTs grown using thermal CVD method.
Dr. Manish Chhowalla
University of Cambridge
Engineering Department
Trumpington Street
Cambridge, CB2 1PZ
UK
+44-1223-766767 (phone)
+44-1223-332662 (fax)
------------------------------------------------------------
Title: Investigation of the growth mechanism of vertically aligned carbon nanotubes using high resolution electron microscopy
Authors: C. Ducati^{1}, M. Chhowalla^{1}, K.B.K. Teo^{1}, I. Alexandrou^{1}, N.L. Rupesinghe^{1}, G.A.J. Amaratunga^{1}, J. Robertson^{1}, W.I. Milne^{1}, A. Papworth^{2}, C.J. Kiely^{2}
Affiliations: ^{1}University of Cambridge, Engineering Department, ^{2}University of Liverpool, Materials Science Department
Abstract:
The growth mechanism of carbon nanotubes from solid-phase catalysts in hydrocarbon atmosphere can be described as a sequence of dissolution and diffusion of atomic carbon into a metal particle, formation of a metastable carbide, precipitation of a stable graphite phase forming the nanotube walls. Vertically aligned carbon nanotubes (VACNTs) have been grown by direct current plasma enhanced chemical vapour deposition (DC PECVD) on a nickel catalytic layer. The CNT film properties, such as average tube diameter, growth rate and areal density, are controlled by the initial thickness of the metal layer. The alignment of the tubes depends on the electric field applied during deposition. VACNTs have been characterised by high resolution electron microscopy (HREM) and scanning transmission electron microscopy (STEM) in order to gain an insight on the role of the catalyst particle in the tip-growth process. Direct evidence of metastable MexC phases that promote the segregation of carbon from the catalyst particle is reported. A detailed study on the growth of VACNTs will be presented. A model similar to that of Baker and Harris [1] is proposed to explain the growth mechanism of VACNTs. [1] R.T.K. Baker, P.S. Harris, in 'Chemistry and Physics of Carbon' ed. P.L. Walker and P.A. Tower (Dekker, New York - 1978).
Ms. Jeongo-O Lee
Chonbuk National University, Physics Dept.
Duckjin Dong, Duckjin Gu, Chonju City, 561-756, S. Korea
Chonju, Chonbuk 561-756
Korea
+82-63-270-3446 (phone)
+82-63-270-3320 (fax)
------------------------------------------------------------
Title: Electrical transport properties in multi-wall carbon nanotube p-p hetero-junction
Authors: J. -O Lee, H. Oh, J. -R. Kim, K.C. Kang, and J.J. Kim, J. Kim , J. W. Park, K.H.Yoo
Affiliations: Chonbuk National University and Korea Research Institute of standards and Sciences.
Abstract:
We have studied the electronic transport properties of hetero-structure junction made of two different multi-wall carbon-nanotubes. The independent measurements on each nanotube revealed that the one show p-type semi-conducting behavior with a gap size of about 300 mV, the other also was p-type semi-conductor with a gap size of about 80 mV. The measured current-voltage characteristics across the hetero-junction show reproducible rectifying diode behavior with highly non-linear transport properties. The forward bias current across the junction increased strongly with increasing the gate bias voltage positively indicating n-type gate response. This diode behavior and n-type gate modulation could be explained by the bending effect of valence band in the hetero-junction
Dr. Gregory C McIntosh
Department of Physics, Seoul National University,

Seoul 151-742,,
Korea
+82-2-8808144 (phone)
+82-2-876-2590 (fax)
------------------------------------------------------------
Title: Electronic Transport Behaviour in Carbon Nanotube Ropes
Authors: G. C. McIntosh^{1}, G. T. Kim^{2} and Y. W. Park^{1}
Affiliations: ^{1}Department of Physics, Seoul National University, Seoul 151-742, Korea, ^{2}Max Planck Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
Abstract:
In this presentation we emphasize interesting behaviour observed for the electronic transport properties of two single-walled carbon nanotube (SWCN) rope samples. For the first sample, the Coulomb blockade regime has been explored. The Coulomb blockade peaks observed display interesting three-way splitting, the cause of which can be related to resonant tunnelling through discrete energy levels of a finite length metallic SWCN within the rope. We also consider the possible role that interactions between `quantum dot' regions within the rope can play in causing such peak splitting. For the second sample, we have explored magnetoresistance behaviour. For a magnetic field applied perpendicular to the rope axis we observe monotonic negative magneto-resistance due to two-dimensional weak localisation within the rope. By contrast, for a magnetic field applied parallel to the rope axis we observe complicated oscillatory behaviour due to the Altshuler-Aronov-Spivak effect. One particular oscillatory mode can be identified which corresponds to closed cylindrical paths around the outer diameter of the SWCN rope. However, overall, due to the composite filamentary nature of the rope and the multitude of closed electron trajectories available, the complicated oscillatory behaviour can be classified as universal conductance fluctuations.
select. Jonathan N Coleman
Trinity College Dublin
Physics Department
Dublin 2
,
Ireland
++353 1 608 3595 (phone)
++353 1 6711759 (fax)
------------------------------------------------------------
Title: Carbon nanotube based composites as electron injection layers in organic light emitting diodes
Authors: JN Coleman, P Fournet, A Drury, B Kilbride, HH Hoerhold* and WJ Blau
Affiliations: Materials Ireland Polymer Research Centre, Trinity College Dublin, Dublin 2, Ireland. * Institut für Organische Chemie und Makromolekulare Chemie, Friedrich-Schiller-Universität Jena, Humboldtstra?e 10, D- 07743, Jena, Germany
Abstract:
Organic light emitting diodes have been fabricated, incorporating carbon nanotube based composites as electron injection layers. At moderate nanotube loading levels, electron injection into M3EH-PPV was increased by over three orders of magnitude. This was accompanied by a substantial increase in electroluminescent efficiency. This is explained by improved current balance leading to higher singlet exciton yield.
Dr. C.Q. Ru
University of Alberta
Department of Mechanical Engineering
Edmonton, Alberta T6G 2G8
Canada
+780-492-4477 (phone)
+780-492-2200 (fax)
------------------------------------------------------------
Title: Interlayer Friction in Multiwall Carbon Nanotubes under bending or high pressure
Authors: C.Q. Ru
Affiliations: University of Alberta
Abstract:
Two questions will be posed regarding the nature of interlayer friction in multiwall carbon nanotubes (MWCNTs) under bending or high pressure : 1. According to the experimental data of Falvo et al (Nature, 1997) on buckling of MWCNTs under bending, it is suggested that the ovalization of the cross-section of MWCNTs under bending would lead to significant reduction of the interlayer spacing and high friction, which would result in an interlocking of adjacent tubes of MWCNTs. 2. The application of an external high pressure to MWCNTs would lead to significant reduction of the interlayer spacing and an interlocking of adjacent tubes, and thus drastically improve the bending stiffness of MWCNTs. The study of these issues could provide an effective way to probe the nature of interlayer friction in MWCNTs. In particular, these studies have significant implications to the design of nanotube-based devices (such as friction-free bearings proposed by Cumings & Zettl, Science 2000).
Dr. Carl D Scott
NASA Johnson Space Center
EM2
NASA Johnson Space Center
Houston, TX 77058
USA
281-483-6643 (phone)
281-244-1301 (fax)
------------------------------------------------------------
Title: IRON CATALYST CHEMISTRY IN HIGH PRESSURE CARBON MONOXIDE NANOTUBE REACTOR
Authors: Carl D. Scott^1, Alexander Povitsky^2, Chris Dateo^3, Tahir Gokcen^3, Richard E. Smalley^4
Affiliations: See additional info below
Abstract:
The high-pressure carbon monoxide (HiPco) technique for producing single wall carbon nanotubes (SWNT) is analyzed using a chemical reaction model coupled with properties calculated along streamlines. Streamline properties for mixing jets are calculated by the FLUENT code using the k-e turbulent model for pure carbon monoxide. The HiPco process introduces cold iron pentacarbonyl diluted in CO, or alternatively nitrogen, at high pressure, ca. 30 atmospheres into a conical mixing zone. Hot CO is also introduced via three jets at angles with respect to the axis of the reactor. Hot CO decomposes the Fe(CO)5 to release atomic Fe. Cluster reaction rates are from Krestinin, et al., based on shock tube measurements. Another model is from classical cluster theory given by Girshick's team. The calculations are performed on streamlines that assume that a cold mixture of Fe(CO)5 in CO is introduced along the reactor axis. Then iron forms clusters that catalyze the formation of SWNTs from the Boudouard reaction on Fe-containing clusters by reaction with CO. Time histories of temperature and dilution that were calculated by the fluid dynamics code FLUENT are inputs for simulating the chemical process along streamlines. Alternative catalyst injection schemes are also evaluated.
Dr. Dmitri V. Golberg
National Institute for Materials Science
Namiki-1-1
Tsukuba, Ibaraki 305-0044
Japan
+81-298-58-5655 (phone)
+81-298-51-6180 (fax)
------------------------------------------------------------
Title: BN and B/N-doped C nanotubes: synthesis, structure, properties and applications
Authors: Dmitri Golberg and Yoshio Bando
Affiliations: National Institute for Materials Science
Abstract:
Multi-walled nanotubes made of B/N-doped C and pure BN were synthesized through thermo-chemical treatments of CVD-grown multi-walled C nanotubes, boron oxide and various metal oxide promoters in a flow of nitrogen at 1700-2000 K using high-frequency induction currents. Nanotube structure and B, C, N atom species distribution were analyzed using a JEM-3000F field emission 300 kV electron microscope equipped with a Gatan 2D-DigiPEELS electron energy loss spectrometer and an energy dispersion X-ray detector, and an Omega filter JEOL-3100 field emission 300 kV electron microscope. Preferential "zigzag" chirality and unique rhombohedral-like stacking between tubular shells were first observed in the BN-rich nanotubes. New approaches for making exclusively open-ended tubes and synthesizing BN nanotubes with definitely preferred even number (2, 4) of tubular shells were developed. In addition, B/N-doped C and BN tube filling with discrete metal clusters or metal nanowires was first carried out. Energy filtered TEM images allowed to discover peapod-like structures in B/N-doped C and BN tubes, existence of heterojunctions between BN-rich and C-rich nanotube domains, and complex nanotubular ropes extending up to several micrometers in length, and composed of C-rich and BN-rich tubes. Nanotube formation mechanism, structural models, thermal and chemical stability, and prospects for technological applications will be discussed in the presentation.
Prof. Pertti J Hakonen
LTL/Helsinki University of Technology
Otakaari 3A
P.O. Box 2200
Espoo, FIN-02015
Finland
358-9-4512964 (phone)
358-9-4512969 (fax)
------------------------------------------------------------
Title: Multiwalled carbon nanotube: Luttinger liquid or not?
Authors: R. Tarkiainen^{1}, M. Ahlskog^{1}, J. Penttil\a^{1}, L. Roschier^{1}, P. Hakonen^{1}, M. Paalanen^{1}, and E. Sonin^{1,2}
Affiliations: ^{1} Low Temperature Laboratory, Helsinki University of Technology, FIN-02015 HUT, Finland, ^{2} The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Abstract:
At low voltages, the tunneling conductance obeys non-Ohmic power law, which is predicted both by the Luttinger liquid and the environment-quantum-fluctuation theories. However, at higher voltages we observe a crossover to Ohm's law with a Coulomb-blockade offset, which agrees with the environment-quantum-fluctuation theory, but cannot be explained by the Luttinger-liquid theory. From the high-voltage tunneling conductance we determine the transmission line parameters of the nanotubes. For the kinetic inductance we obtain {\it l_{kin}} = 0.5 mH/m, which indicates that the average number of conducting layers in our nanotubes is 8 (out of about 20) at frequencies of {\it f} = 0.5 - 10 THz.
Dr. Markus E Ahlskog
Low Temperature Laboratory, Helsinki University of Technology
Otakaari 3A
Espoo, 02015
Finland
358-9-4512964 (phone)
358-9-4512969 (fax)
------------------------------------------------------------
Title: Multiwalled carbon nanotubes as nanoscale electronic devices
Authors: M. Ahlskog, R. Tarkiainen, L. Roschier, and P. Hakonen
Affiliations: Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland
Abstract:
Carbon nanotubes may form the building blocks of future nanoscale electronic devices. We have measured the electronic characteristics of single electron transistors (SET) fabricated from multiwalled carbon nanotubes (MWNT) in various configurations. Moreover, we have used MWNTs synthesized both by the arc-discharge (AD) and chemical vapour deposition (CVD) methods. Both the mechanical and electronic properties of these tubes are very different. Generally CVD tubes have a clearly higher density of defects. In devices fabricated from AD tubes we observe clear Coulomb blockade oscillations at low temperatures. In a SET where the central island is formed by a MWNT, a second MWNT crossing the former can be utilized to gate the source-drain current. In another device where the MWNT is suspended above the substrate between the electrodes, we measure an extremely high charge sensitivity of 6x10^{-6} e/sqrt(Hz) at 45 Hz, comparable to the best of the conventional SETs. In CVD tubes we measure a clearly higher resistance and irregular Coulomb blockade oscillations.
Dr. Kazu SUENAGA
JST
Dept. Physics
Meijo Univ.
Nagoya, Aichi 468-8502
Japan
+81-52-834-4001 (phone)
+81-52-834-4001 (fax)
------------------------------------------------------------
Title: Nano-EELS diagnoses of hybrid nanotubes, nanocoils, and nanocables
Authors: K. Suenaga
Affiliations: JST
Abstract:
Since the discovery of pure carbon nanotubes, researches for similar nanostructures involving non-carbon elements have been stimulated. The predicted electronic properties of these multi-element nanotubes are variable and essentially determinable by their chemical composition. Therefore the controlled production of hetero-junctions of such nanotubes can lead to the creation of a nanometer scale device with tailored electronic properties. A characterization tool with high spatial resolution is indispensable for the successful realization of such devices with anticipated geometry. Spatially resolved electron energy loss spectroscopy (EELS) is quite well-suited to such kinds of analysis: using an incident probe generated by a scanning transmission electron microscope (STEM), one is able to simultaneously perform elemental mapping and chemical state assignment at a sub-nanometer spatial resolution. Examples of hybrid nano-structures such as nanocoils, nanocables and B-C-N nanotubes those are promising candidates for nano-structured electronic devices, will be presented.
Dr. Christophe LAURENT
Universite Paul-Sabatier
CIRIMAT, UMR CNRS 5085 / LCMIE
Bat 2R1, Universite Paul-Sabatier
Toulouse cedex 4, 31062
France
+33 561 55 61 22 (phone)
+33 561 55 61 63 (fax)
------------------------------------------------------------
Title: A Study of the Formation of Single- and Double-Walled Carbon Nanotubes by a CVD Method
Authors: A. Peigney1, P. Coquay2, E. Flahaut1, R. E. Vandenberghe2, E. De Grave2, Ch. Laurent1
Affiliations: 1 Universite Paul-Sabatier/CNRS, Toulouse, France and 2 University of Gent, Gent, Belgium
Abstract:
The reduction in H2/CH4 atmosphere of aluminum-iron oxides produces metal particles small enough to catalyze the formation of single-walled carbon nanotubes. Several experiments have been made using the same temperature profile and changing only the maximum temperature (800-1070°C). Characterizations of the catalyst materials are performed using notably 57Fe Mössbauer spectroscopy. Electron microscopy and a macroscopical method are used to characterize the nanotubes. The nature of the iron species (Fe3+, a-Fe, g-Fe-C, Fe3C) is correlated to their location in the material. The nature of the particles responsible for the high-temperature formation of the nanotubes is probably an Fe-C alloy which is, however, found as Fe3C by post-reaction analysis. Increasing the reduction temperature increases the reduction yield and thus favors the formation of surface metal particles, thus producing more nanotubes. The obtained carbon nanotubes are mostly single-walled and double-walled with an average diameter close to 2.5 nm. Several formation mechanisms are thought to be active. In particular, it is shown that the second wall can grow inside the first one but that subsequent ones are formed outside. It is also possible that under given experimental conditions, the smallest (< 2 nm) catalyst particles preferentially produce double-walled rather than single-walled carbon nanotubes.
Mr. Mark R Buitelaar
Institut für Physik, Universität Basel
Klingelbergstr. 82
Basel, CH-4056
Switzerland
+41-61-2673779 (phone)
+41-61-2673784 (fax)
------------------------------------------------------------
Title: ELECTRONIC TRANSPORT IN MULTI - WALLED CARBON NANOTUBES
Authors: M.R. Buitelaar^{1}, M. Iqbal^{1}, T.Nussbaumer^{1}, L. Forr{\'o}^{2} and C. Sch{\o}nenberger^{1}
Affiliations: (1) Institut f{\"u}r Physik, Universit{\"a}t Basel, Klingelbergstr. 82, CH-4056 Basel, Switzerland (2) Institut de G{\'e}nie Atomique, EPFL, CH-1015 Lausanne, Switzerland
Abstract:
We have studied the differential conductance of single multi-walled carbon nanotubes (MWNT’s) as a function of bias and gate voltage. Clear traces of coulomb blockade could be observed for MWNT`s connected to Au electrodes, even when the average two-terminal conductance was high ($\sim 2e^{2}/h$ at 280 mK). At such intermediate Au - MWNT transparancies, i.e. low enough to see the remainders of coulomb blockade and high enough to reach conductances of $2e^{2}/h$, one can expect higher-order tunnelling processes to play an important role in the electron transport. An example of such is the Kondo effect which was observed for the first time in single wall tubes by Nygard $et al^{1}$. We obtained very similar results on a MWNT and studied the Kondo resonance as function of temperature and magnetic field. Preliminary measurements of MWNT`s contacted to superconducting electrodes show a considerable resistance drop below the $T_C$ of the contacts. Upon applying a small magnetic field, the sample behaves similar to measurements performed with normal gold contacts. [1] Nygard. J $et al$. Nature $\b{408}$, 342 (2000).
Dr. Ulrich S. Schwarz
Max-Planck-Institute of Colloids and Interfaces
Theory Division
Potsdam, 14424
Germany
0331-5679610 (phone)
0331-5679602 (fax)
------------------------------------------------------------
Title: Scaling laws for van der Waals interaction of hollow nanoparticles
Authors: U. S. Schwarz^{1} and S. A. Safran^{2}
Affiliations: ^{1} MPI of Colloids and Interfaces, Golm, Germany, ^{2} Weizmann Institute, Rehovot, Israel
Abstract:
We present theoretical investigations of the effect of van der Waals interactions on crystal properties, phase behavior and adhesion properties of hollow nanoparticles made from layered material like C or WS$_2$. Since the van der Waals interaction scales linearly with radius R, the heat of sublimation is larger than for molecular scale van der Waals solids. Since the interaction range between particles scales inversely with R, the gas-liquid coexistence disappears from the phase diagram for particle radii in the range of 1-3 nm (depending on wall thickness h). Upon van der Waals adhesion to a substrate, both nanospheres and nanotubes can deform considerably, albeit with different scaling laws in regard to R and h.
Dr. Kim Bolton
Molecular Physics
Experimental Physics
Goteborg University and Chalmers University of Technology
Goteborg, SE-41296
Sweden
+46-31-7723496 (phone)
+46-31-7723294 (fax)
------------------------------------------------------------
Title: Computational studies of catalysed nanotube growth
Authors: Kim Bolton and Arne Rosén
Affiliations: Experimental Physics, Goteborgs University and Chalmers University of Technology
Abstract:
Although metal catalysts are often used in the production of single-walled carbon nanotubes (SWNTs), the catalytic growth mechanism is not fully understood. Increased knowledge of the role of the catalyst in nanotube nucleation and production is not merely of fundamental interest, but will also assist in the quest to manufacture separate, defectless SWNTs that have a desired chirality. In spite of this there has been a relatively limited number of computational studies of catalysed nanotube growth. This is due, in part, to the long time required for growth and the difficulty of modelling transition metal catalysts accurately. In this work we discuss ab initio and semi-empirical methods to study iron-catalysed SWNT production. Ab initio calculations, which are computationally expensive, yield accurate structural and geometric information, and semi-empirical direct dynamics simulations provide insight into the catalytic growth mechanism.
Dr. Jeannette M. Benavides
NASA/Goddard Space Flight Center
Greenbelt Rd.
Code 562
Greenbelt, MD 20771
USA
301-286-4368 (phone)
301-286-1695 (fax)
------------------------------------------------------------
Title: A controlled Arch Welding and Separation Processes for Carbon Nanotubes
Authors: Jeannette Benavides, Ashok Sharma and Harry Shaw
Affiliations: NASA/Goddard Space Flight Center
Abstract:
A modified Arch Welding process for the synthesis of carbon nanotubes will be described. It was found that the production of specific kinds of carbon nanotubes can be controlled by key variables. A separation procedure for the carbon nanotubes that does not involved acids will also be described. Characterization of the carbon nanotubes by SEM, TEM and Raman together with applications of carbon nanotubes for NASA's future missions will be discussed.
Mr. Michael Holzinger
Institute of Organic Chemistry
Henkestraße 42
Erlangen, Bavaria 91054
Germany
+49 9131 8522548 (phone)
+49 9131 8526864 (fax)
------------------------------------------------------------
Title: The Chemistry of Single Walled Carbon Nanotubes
Authors: Michael Holzinger and Andreas Hirsch
Affiliations: Institute of Organic Chemistry, Henkestr.42, Erlangen, Germany
Abstract:
In SWNT chemistry two types of derivatization are in principle possible: the amidation or esterification of the carboxylic acid groups of oxidized SWNT material and adding reactive groups onto the sidewalls. For derivatization of the carboxylic acid groups a large variety of methods are described (e.g. activation of the carboxyls by SOCl_{2}, DCC and EDC). In contrast, the reactivity of the sidewalls has received very little attention. From the chemist's point of view, SWNT sidewalls appear to be an intermediate form between graphite and fullerenes. On the one hand, the curved \{pi}-system of the exohedral region should have an increased electron density compared to planar graphite. On the other hand, having a diameter of about 1.4 nm the moderate curvature should result in less nucleophilic reactivity at the annealed benzene rings than found in C_{60}. For functionalisation of the SWNT sidewalls special reagents are required which exhibit pronounced reactivity. The reactions of C_{60} with nitrenes, carbenes and radicals have been described in detail. Here we present similar types of reaction with SWNTs prepared by arc discharge.
Dr. Davide Ceresoli
International School for Advanced Studies (SISSA)
via Beirut 2
Trieste, 34014
Italy
+39-040-3787448 (phone)
+39-040-3787528 (fax)
------------------------------------------------------------
Title: Structural stability and electronic structure of boron nanotubes
Authors: D. Ceresoli (a,b), E. Tosatti (a,b,c)
Affiliations: (a) International School for Advanced Studies (SISSA), via Beirut 2, I-34014 Trieste, Italy; (b) Istituto Nazionale Fisica della Materia (INFM),Unità Trieste-SISSA, Trieste, Italy;(c) International Centre for Theoretical Physics (ICTP),Trieste, Italy
Abstract:
After the recent discovery of superconductivity in a new class of inorganic compounds, metal-intercalated boron analogues of graphite, we decided to address the existence of nanotubes, made up of boron in a honeycomb structure, similar to carbon nanotubes. Using first-principle total-energy methods, we investigated the structural stability of some boron nanotubes, and found them to be metallic by band-structure calculations. The cohesion of the bare boron tube is relatively poor, but its bending strain energy is comparable to those of C and BC analogues. Then we investigated the effect of the insertion of metal atoms inside the nanotubes. While magnesium does not seem strongly stabilized, we found that a constructive interaction occurs with aluminum atoms, which strongly stabilize the structure of the smallest boron nanotubes.
Prof. Daniel E. Resasco
University of Oklahoma
100 East Boyd St.
CEMS
Norman, Oklahoma OK 73019
USA
(405)325-4370 (phone)
(405)325-5813 (fax)
------------------------------------------------------------
Title: Cost-effective Controlled Production of Single-Walled Nanotubes
Authors: W. E. Alvarez, L. Balzano, J. E. Herrera, D. E. Resasco
Affiliations: University of Oklahoma
Abstract:
The rate of discovery of new and exciting properties of SWNT has yet to slacken. However, the development of commercial applications will remain a dream as long they are made by the laboratory methods available today. The full realization of the technological potential of nanotubes is contingent upon the development of industrial- scale synthesis. Applications such as SWNT-reinforced composites will never be realized as long as nanotubes are produced at rates of no more than grams per hour; an important step in advancing this technology is the development of techniques to produce tons of nanotubes per year. We have developed a "controlled production" method of SWNT. This term implies the ability to control the selectivity towards SWNT by changing catalyst formulations and operating conditions, combined with an effective purification strategy and a quantitative determination of the SWNT obtained. The use of heterogeneous catalysts allowed us to tailor the material in such a way that selectivity and yield are maximized. The method employed involves the disproportionation of CO at moderate pressure and temperature, which result in a scalable, cost-effective process. Optimal reaction conditions including temperature, pressures, gas-space velocities, catalyst composition and pre-treatments, as well as purification methods, will be reported.
Dr. Walter E. Alvarez
University of Oklahoma
100 East Boyd St.
CEMS
Norman, Oklahoma OK 73019
USA
(405) 325-9178 (phone)
(405) 325-5813 (fax)
------------------------------------------------------------
Title: Qualitative and Quantitative Assessment of the SWNT Produced by the Controlled Catalytic Production Before and After Purification
Authors: F. Pompeo, L. Balzano, H. Barraza, J. E. Herrera, E. O'Rear, W. E. Alvarez, D. E. Resasco
Affiliations: University of Oklahoma
Abstract:
The quantification of the SWNT yield and the evaluation of their chemical characteristics are essential components in the development of a production process. In this particular study, the SWNT were produced by vapor-phase disproportionation of CO over a heterogeneous catalyst. Temperature programmed oxidation has been used to determine the total carbon yield as well as the selectivity to SWNT. The results of this quantitative method were corroborated by Raman and TEM/SEM analysis. After the SWNT production, the materials were subjected to purification steps that involve attack of the catalyst support and metals with a combination of basic and acid solutions. This process results in a different degree of functionalization of the tubes. The characterization of the chemical nature of the resulting functional groups was conducted by XPS and FTIR. To quantify the density of functional groups a combination of TPD-TPO and XPS was employed. The response of the tubes prepared by the catalytic method to the basic/acid attacks was compared to those of tubes prepared by other methods (arc discharge and laser ablation). Also, the structure of these tubes (bundle diameter, tube diameter, tube length), as measured by AFM, TEM and Raman, was compared to those commercially available.
Dr. Hyoung Joon Choi
University of California at Berkeley
Department of Physics
366 Le Conte Hall # 7300
Berkeley, California 94720-7300
U.S.A.
1-510-642-1031 (phone)
1-510-643-9473 (fax)
------------------------------------------------------------
Title: Electronic transport and structure in carbon nanotube junctions
Authors: Hyoung Joon Choi^{1}, Jisoon Ihm^{2}, Young-Gui Yoon^{1,3}, Steven G. Louie^{1,3}, and Marvin L. Cohen^{1,3};
Affiliations: ^{1}Department of Physics, University of California at Berkeley, Berkeley, California 94720, U.S.A., ^{2}Department of Physics, Seoul National University, Seoul 151-742, Korea, ^{3}Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, U.S.A.
Abstract:
With an intramolecular junction of a metallic and a semiconducting carbon nanotube, we study the electronic current and structure along the junction at finite bias voltage using a self-consistent tight-binding method. The atomic arrangement and charge redistribution along the junction at finite current density are taken into account in our calculation by nearest-neighbor hopping of \{pi}-electrons and by a self-consistent Hartree-type electrostatic interaction among the electrons. Our result shows zero current at smaller bias voltage than the bandgap of the semiconducting tube, and superlinear increase of current at larger bias voltage. The self-consistent charge density shows maximal fluctuation of 3 percents in the 1 nm long region at the junction, and smaller Friedel oscillation in the metallic part. The screened electrostatic potential, at finite bias voltage, is almost constant in the metallic part and drops linearly in the semiconducting part.
Dr. Michael Thorwart
Department of Applied Physics
Delft University of Technology
Lorentzweg 1
Delft , 2628 CJ
The Netherlands
+31-15-278-2898 (phone)
+31-15-278-1203 (fax)
------------------------------------------------------------
Title: Resonant tunneling in carbon nanotubes in presence of two tunneling junctions
Authors: M. Thorwart, M. Grifoni, H.W. Ch. Postma, and C. Dekker
Affiliations: Delft University of Technology
Abstract:
We investigate theoretically resonant tunneling in nanotubes containing two sharp bends. Because the bends act as tunneling junctions, the system constitutes a one-dimensional quantum dot attached to one-dimensional leads. The linear as well as the nonlinear transport are investigated within a master equation approach as well as by means of precise {\it ab-initio} real-time path-integral simulations. By treating the strong Coulomb interaction among the quasi-one-dimensional electrons within the framework of Luttinger liquids, a characteristic power-law behavior for the differential conductance is extracted. Our results are applied to explain recent experimental findings for transport in metallic nanotubes containing two sharp bends. These local deformations, acting as tunnel junctions, have been designed with the tip of an atomic force microscope.
Dr. Kristina Edström
Department of Materials Chemistry, Uppsala University
Ångström Laboratory
Box 538
Uppsala, SE-751 21
Sweden
+46-18-4713713 (phone)
+46-18-513548 (fax)
------------------------------------------------------------
Title: Vanadium Oxide Nanotubes as Cathode Materials in Rechargeable Lithium Batteries
Authors: Kristina Edström, Sara Nordlinder, Torbjörn Gustafsson, Jun Lu and Eva Olsson
Affiliations: Departments of Materials Chemistry and Analytical Materials Physics, The Ångström Laboratory, Uppsala University, SE-751 21 Uppsala, Sweden
Abstract:
Vanadium oxide in the form of scroll-like nano-rolls is here demonstrated as a cathode material for rechargeable lithium batteries. The rolls consist of several vanadium oxide layers, separated by structure-directing agents (templates). Two different types of nanotubes, one with hexadecylamine (C_{16}H_{33}NH_{2}) and another with dodecylamine (C_{12}H_{25}NH_{2}) as templating molecules have been studied. In addition, the effect of Na+-exchange on the microstructure of the latter is analysed. By the use electrochemical techniques, {\it in situ} X-ray diffraction, electron spectroscopic imaging and high angle annular dark field imaging, a picture of the internal structure of the tubes and its function as a cathode material have evolved. The battery performance is shown to be closely dependent on type of lithium salt used in the electrolyte. The highest capacity (>200 mAh/g) is found using Na+-exchanged material and an electrolyte containing LiN(SO_{2}CF_{3})_{2} as the lithium salt. The nano-rolls can be charged/discharged at least 100 cycles with preservation of the tubular structure. Details of the tubular structure and lithium insertion/extraction mechanisms will be discussed in the light of the performance as battery material.
Prof. Milan Damnjanovic
Faculty of Physics, University of Belgrade
Studentski trg 12-16
POB 368
Belgrade, Serbia 11001
Yugoslavia
(..381 11) 630 152 (phone)
(..381 11) 328 26 19 (fax)
------------------------------------------------------------
Title: Symmetry Principles of Friction --- Nanotubes
Authors: Milan Damnjanovic, Tatjana Vukovic and Ivanka Milosevic
Affiliations: Faculty of Physics, University of Belgrade, POB 368, YU-11001 Belgrade
Abstract:
The symmetries of two compounds significantly affect their interaction. This is sublimated within three basic principles, which are applied to the carbon nanotubes (finite and infinite) to explain recently proposed [1] and observed [2] low friction effects. The friction decreases on account of the symmetry breaking mechanism, which can produce even the super-slippery interaction: the Goldstone mechanism makes that the walls in an infinite incommensurate double-wall nanotube freely slide. As a general recipe for lubricant selection, the results may be of interest in tribology. [1] M. Damnjanovic, I. Milosevic, T. Vukovic and R. Sredanovic, Phys. Rev. B {\bf 60} (4) (1999) 2728. [2] John Cumings and A. Zettl, Science, {\bf 289} (2000) 602.
Dr. Ivanka Milosevic
Faculty of Physics, University of Belgrade
Studentski trg 12-16
POB 368
Belgrade, Serbia YU-11001
Yugoslavia
(..381 11) 630 152 (phone)
(..381 11) 328 26 19 (fax)
------------------------------------------------------------
Title: PLASMON EXCITATIONS IN ISOLATED SWCNT
Authors: I. Milosevic, T. Vukovic, S. Dmitrovic, M. Damnjanovic
Affiliations: Faculty of Physics, POB 368, YU-11001 Belgrade
Abstract:
Optical conductivity tensor for isolated single-wall carbon nanotubes (SWCNT) of arbitrary chirality is found. The calculation is based on the maximally reduced tight binding method [1] and dipole approximation. The line group symmetry of the SWCNT [2] is taken into account and the matrix elements of the momentum operator are calculated exactly. The result is used to interpret the EELS measurements of the tubes with the same radii showing different behaviours (almost doubled intensity and 3 eV peak position shift) [3]: the effect is related to the parities of the electronic states and strongly depends on the polarization of the perturbing field. The interpretation can be used to complete the identification of the geometrical structure of the tubes under study. [1] M. Damnjanovic, T. Vukovic, I. Milosevic, J. Phys. A {\bf 33} (2000) 6561. [2] M. Damnjanovic, I. Milo\v sevic, T. Vukovic and R.Sredanovic, Phys. Rev. B {\bf 60} (4) (1999) 2728. [3] T. St\"ockli, Ph. D. Thesis, Lausanne, EPFL (1999).
Dr. Lyubov G. Bulusheva
Institute of Inorganic Chemistry SB RAS
pr. Ak. Lavrent'eva, 3
Novosibirsk, 630090
Russia
+7(3832) 341366 (phone)
+7(3832)344489 (fax)
------------------------------------------------------------
Title: Defects in the catalytic multiwall carbon nanotubes
Authors: L.G. Bulusheva,^1 A.V. Okotrub,^1 I.P. Asanov,^1 A. Fonseca^2 and J. B.Nagy^2
Affiliations: ^1Institute of Inorganic Chemistry SB RAS, pr. Ak.Lavrent’eva 3, Novosibirsk 630090, Russia; ^2Laboratoire de Résonance Magnétique Nucléaire, Facultes Universitaires Notre-Dame de la Paix, Rue de Bruxelles 61, 5000 Namur, Belgium
Abstract:
Thermal decomposition of hydrocarbons on the metal catalyst yields bent and curved multiwall nanotubes, the layers of which are often wavy and segmented. Such structural distinguishes from the typical arc-produced multiwall carbon nanotubes can cause the difference in the electronic structure for two tube kinds. To check it the methods of X-ray emission and X-photoelectron spectroscopy were used. Comparison between measured spectra detected that, actually, the CK\alpha spectrum of catalytic nanotubes is characterized by enhanced density of pi-occupied states and the C 1s line of this sample is expanded toward both lower and higher binding energy regions. To reveal what type of structural defects can explain the experimental data the tubular models incorporated pentagon-heptagon pairs, sp^3-hybridized atoms, and incomplete bonds were calculated using quantum-chemical program AM1. Carbon K\alpha and 1s lines were found to be practically unaffected by inserting pentagon and heptagon into the hexagonal network on diametrically opposite sides of tube. The adjacent position of defect pair gives the better while still not adequate fit to the experiment. However, the interlayer linkages and holes in the carbon network may provide the expected spectral changes.
Mr. Freek Langeveld
Delft University of Technology
Department of Applied Physics and DIMES, Theoretical Physics Sec
Lorentzweg 1
Delft, 2628 CJ
The Netherlands
+31 (15) 278 1596 (phone)
+31 (15) 278 1203 (fax)
------------------------------------------------------------
Title: Excitonic-Insulating States in Carbon Nanotubes
Authors: Freek Langeveld and Gerrit E. W. Bauer
Affiliations: Delft University of Technology, Department of Applied Physics and DIMES, Theoretical Physics Section
Abstract:
It has been demonstrated [1] that a long-lived spin accumulation can be injected into carbon nanotubes (CN's). Motivated by this experimental result, we theoretically consider a charge-neutral semiconducting CN where this spin accumulation corresponds to a quasi-equilibrium density of electrons and holes (in the lowest conduction and highest valence band, respectively) of the same spin direction. In mean-field theory, such a "spin-doped" (and, at first sight, conducting) system is unstable with respect to condensation of spin-triplet excitons, which are bound by the attractive electron-hole Coulomb interaction. The resulting ground state does not conduct and is called: "excitonic insulator". Taking into account a screened Coulomb interaction, we calculate the quasiparticle dispersion and find a gap (different from and not to be confused with the band gap of the intrinsically semiconducting CN) which decreases when the amount of spin (and hence electron-hole pair) doping is increased, but, suprisingly, does not vanish in the high-density regime, where the single-particle dispersion is almost linear and backscattering is strongly suppressed --- as in metallic CN's. In the latter regime, we discuss the validity and significance of our mean-field approximation by comparison with the Tomonaga-Luttinger liquid theory. [1] Tsukagoshi {\em et al}, Nature {\bf 401}, 572-574 (1999).
Dr. Sebastian Eggert
Chalmers Technical University
Theoretical Physics
Chalmers
Goteborg, 41296
Sweden
+46 31 7723190 (phone)
+46 31 7723204 (fax)
------------------------------------------------------------
Title: Curvature and Hybridization Effects in Carbon Nanotubes
Authors: Alex Kleiner and Sebastian Eggert
Affiliations: Theoretical Physics, Chalmers, Goteborg, Sweden
Abstract:
The curvature effects in carbon nanotubes are studied analytically as a function of chirality. The $\pi$-orbitals are found to be significantly rehybridized in all tubes, so that they are never normal to the tubes' surface. This results in a curvature induced gap in the electronic band-structure, which turns out to be larger than previous estimates. The tilting of the $\pi$-orbitals should be observable by atomic resolution scanning tunneling microscopy measurements.
Mr. Alex Kleiner
Institute for theoretical physics
Chalmers university of technology
Gothenburg, 412 96
Sweden
++46 31 772 3171 (phone)
(fax)
------------------------------------------------------------
Title: Effects of a perpendicular magnetic field on the nanotube conductivity
Authors: Alex Kleiner and Sebastian Eggert
Affiliations:
Abstract:
We study theoretically the conductivity of a metallic nanotube under a perpendicular magnetic field. The density of states and the backscattering probability vary with the field, resulting in fluctuations of the conductivity as a function of the magnetic field.
Dr. Enzo Menna
Dipartimento di Chimica Organica - Università di Padova
Via Marzolo, 1
PADOVA, 35131
ITALY
+39.049.8275660 (phone)
+39.049.8275239 (fax)
------------------------------------------------------------
Title: Synthesis of soluble single-walled carbon nanotube derivatives
Authors: E. Menna^{1}, F. Della Negra^{1}, M. Cavallaro^{1}, M. Maggini^{1}, G. Scorrano^{1}, M. Meneghetti^{2}, F. Paolucci^{3}, M. Battagliarin^{4}
Affiliations: ^{1} Dipartimento di Chimica Organica - Università di Padova, ^{2} Dipartimento di Chimica Fisica - Università di Padova, ^{3} Dipartimento di Chimica "G. Ciamician" - Università di Bologna, ^{4} Dipartimento di Chimica Fisica - Università di Venezia
Abstract:
Most studies on single-wall carbon nanotubes (SWNT) are physical investigations of solid state properties, while the chemical manipulation of nanotubes is still hampered by their insolubility and their extremely low reactivity. Some different approaches have been reported so far to the problem of bringing nanotubes to solution, such as pristine nanotubes suspension, inclusion in polymer matrices, sidewall functionalization. The approach we followed, reported by Smalley and coworkers^{1} and by Haddon and coworkers^{2, 3}, is based on the shortening of SWNT by means of an oxidative cutting process. Carboxylic functions formed at the edges can be conveniently used for further functionalizations. Here we report the synthesis and characterization of a SWNT derivative bearing poly(ethylene glycol) (PEG) chains that shows solubility in polar and non polar organic solvents. The product has been characterized by Raman spectroscopy, IR, NMR and some preliminary studies have been performed to evaluate photophysical properties, EPR and electrochemical behavior in solution. 1. J. Liu et al. {\it Science} {\bf 1998}, {\it 280}, 1253-1256. 2. J. Chenet al. {\it Science} {\bf 1998}, {\it 282}, 95-98. 3. M. A. Hamon et al. {\it Advanced Materials} {\bf 1999}, {\it 11}, 834-840,786.
Dr. Seung Mi Lee
Fritz-Haber-Institut der Max-Planck-Gesellschaft
Faradayweg 4-6
Berlin, D-14195
Germany
+49-30-8413-4870 (phone)
+49-30-8413-4701 (fax)
------------------------------------------------------------
Title: Hydrogen Storage Mechanism in Single-Walled Carbon Nanotubes
Authors: Seung Mi Lee1,2, Young Hee Lee1,3,*, Gotthard Seifert4, and Thomas Frauenheim4
Affiliations: 1 Department of Semiconductor Science and Technology, and Semiconductor Physics Research Center, Jeonbuk National University, Jeonju, Korea 2 Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany 3 School of Natural Sciences, Sung Kyun Kwan University, Suwon, Korea 4 Theoreticsche Physik, Universität-GH Paderborn
Abstract:
A novel mechanism of hydrogen storage in carbon nanotubes is proposed by using the density functional calculations. Several key intermediate states are identified for hydrogen adsorption. Up to the coverage of 1.0, hydrogen atoms chemisorb on the nanotube wall with either an arch type or a zigzag type. Then, hydrogen can be further stored inside the nanotubes at higher coverage as a molecular form. Hydrogen atoms can be inserted into the nanotubes through the tube wall via flip-in and/or kick-in mechanism with activation barriers of 1.5 and 2.0 eV, respectively. In the hydrogen extraction process, hydrogen molecules inside a nanotube firstly dissociates onto the inner wall with an activation barrier of 1.6 eV. Secondly, hydrogen atoms at the interior of the tube wall are further extracted to the outer wall by the flip-out mechanism with an activation barrier of 2.0 eV. Our theoretical calculations support the experimental observations of electrochemical hydrogen storage in nanotubes.
Dr. Seung Mi Lee
Fritz-Haber-Institute der Max-Planck-Gesellschaft
Faradayweg 4-6
Berlin, D-14195
Germany
+49-30-8413-4870 (phone)
+49-30-8413-4701 (fax)
------------------------------------------------------------
Title: Unzipping of Carbon Nanotubes
Authors: Seung Mi Lee1,2, Young Hee Lee1,3, and Thomas Frauenheim4
Affiliations: 1 Department of Semiconductor Science and Technology, and Semiconductor Physics Research Center, Jeonbuk National University, Jeonju, Korea 2 Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany 3 School of Natural Sciences, Sung Kyun Kwan University, Suwon, Korea 4 Theoreticsche Physik, Universität-GH Paderborn
Abstract:
We investigate the unzipping of carbon nanotubes using density-functional calculations. Series of dangling bonds along the tube axis near the tip of nanotubes are intentionally created and further annealed by high temperate molecular dynamics simulations. This result in the unzipping of nanotube and subsequent molecular dynamics leads to the unzipping, eventually forming graphite flakes. The disintegration of nanotubes with an acid treatment will be further discussed.
Dr. Apostolos G. Marinopoulos
Laboratoire des Solides Irradies, CNRS-CEA
Ecole Polytechnique
Palaiseau, F-91128
France
+ 01 6933 4514 (phone)
+ 01 6933 3022 (fax)
------------------------------------------------------------
Title: Ab initio calculation of the absorption and energy-loss spectra of a bundle of carbon nanotubes
Authors: A. G. Marinopoulos^{1}, Lucia Reining^{1}, Angel Rubio^{1,2} and Valerio Olevano^{1}
Affiliations: ^{1} Laboratoire des Solides Irradies, CNRS-CEA, Ecole Polytechnique, F-91128 Palaiseau, France, ^{2} Departamento de Fisica de Materiales, Facultad de Ciencias Quimicas, Universidad del Pais Vasco/Euskal Herriko, Unibertsitatea, Apdo. 1072, 20018 San Sebastian/Donostia, Basque Country, Spain
Abstract:
The frequency-dependent dielectric response function, optical absorption and energy-loss spectra (EELS) have been calculated for a solid of (5,5) armchair carbon nanotubes. We have started from a DFT-LDA ground state calculation using norm-conserving pseudopotentials. The spectra were then obtained in the random phase approximation (RPA) and in the time-dependent local-density approximation (TDLDA), including local field (LF) effects. The response function and spectra were determined for different polarizations and wave-vectors of the exciting light or electrons. Both LF and the polarization are expected to be important for nanotubular structures which possess a high degree of structural inhomogeneity and anisotropy. We discuss our findings in the light of recent theoretical calculations and experimental observations (EELS, optical absorption) of single-wall (SWNT) and multi-wall (MWNT) nanotubes and nanotube bundles.
Mr. Mihail D. Croitoru
Univ. of T\ubingen, Inst. f\ur Angewandte Physik
Auf der Morgenstelle 10
T\ubingen , 72076
Germany
+49 (0)7071 297 3366 (phone)
+49(0)7071 29 5093 (fax)
------------------------------------------------------------
Title: Non-contact scanning force microscopy induced CVD: first attempts towards contacting nanotubes on an insulating substrate
Authors: M. D. Croitoru^{1}, A. H\ochst^{1}, W. Clauss^{1}, S. Roth^{2}, D. P. Kern^{1}
Affiliations: ^{1} Univ. of T\ubingen, Inst. f\"ur Angewandte Physik, Auf der Morgenstelle 10, D-72076 T\"ubingen, ^{2} Max-Planck-Inst. f\"ur Festk\"orperphysik, Heisenbergstr. 1, D-70569 Stuttgart
Abstract:
Using a Scanning Force Microscope (SFM) a new single-step additive process is investigated for electrically contacting carbon nanotubes (CN) on a non-conducting surface. To this effect, vapors of a organometallic precursor are adsorbed to the surface of a substrate with pre-patterned conducting regions, e.g. wiring patterns to which pre-deposited nanotubes on the surface shall be connected. In non-contact imaging mode the SFM tip can be positioned on a conducting region from which a contact is to be made to a CN. A bias voltage is applied between the conducting cantilever/tip and the conducting regions of the sample, resulting in the formation of metal containing deposits at the tip location. Starting from the conducting region the tip is moved across the non-conducting region where adsorbed organometallic molecules are decomposed to form metallic features while the tip-sample current is monitored. In this way a conducting bridge from the patterned electrodes to the CN could be formed. This procedure can be performed at room temperature in air with a reservoir of organometallic material close-by. While a similar effect has been previously obtained using a scanning tunneling microscope on conducting substrates, the exact nature of the SFM-based process is still being investigated.
Dr. Alekber Yu Kasumov
Starlab
Engelandstraat 555
Ukkel
Brussels, 1180
Belgium
(phone)
(fax)
------------------------------------------------------------
Title: Superconductivity in Carbon Nanotubes
Authors: A.Yu. Kasumov^{1}, R. Deblock^{2}, M. Kociak^{2}, B. Reulet^{2}, H. Bouchiat^{2}, S. Gu\'eron^{2}, I.I. Khodos^{3}, Yu.B. Gorbatov^{3}, V.T. Volkov^{3}, C. Journet^{4}, P. Bernier^{4}, M. Burghard^{5}
Affiliations: ^{1}Starlab, Brussels, BELGIUM. ^{2}Laboratoire de Physique des Solides, Associ\'e au CNRS, Orsay, FRANCE. ^{3}Institute of Microelectronics Technology and High Purity Materials, RAS, Chernogolovka, RUSSIA. ^{4}GDPC University of Montpellier, FRANCE. ^{5}Max Plank Institute, Stuttgart, GERMANY.
Abstract:
We show experimental evidence of induced and intrinsic superconductivity in carbon nanotubes. The supercurrent is observed in a single 1nm diameter SWNTs, in individual crystalline ropes containing about 100 nanotubes and also on multiwalled tubes. These samples are suspended as strings between two superconducting (double layer Au-Re, Au-Ta or Sn film) and normal (double layer Au-Pt film) electrodes. The critical current of samples, extensively studied as function of temperature and magnetic field, presents unusual features which are not observed in ordinary Superconducting-Normal-Superconducting junctions and can be related to the strong 1D character of these samples. We also show evidence of a huge sensitivity of dc transport properties of tubes to electromagnetic radiation in the radio-frequency range.
Dr. Lu-Chang Qin
JST Nanotubulite Project
NEC Corp.
34 Miyukigaoka
Tsukuba, Ibaraki 305-8501
Japan
+81-298-561940 (phone)
+81-298-501366 (fax)
------------------------------------------------------------
Title: Identification and Properties of 4A Smallest Carbon Nanotubes
Authors: Lu-Chang Qin, Xinluo Zhao, Kaori Hirahara, Yoshiyuki Miyamoto, Yoshinori Ando, Sumio Iijima
Affiliations: JST Nanotubulite Project, Meijo University, NEC Corp.
Abstract:
The smallest carbon nanotube that remains stable energetically has diameter of 4A. We have produced such nanotubes employing an arc-discharge technique in hydrogen atmosphere and have identified them with high-resolution electron microscopy aided with extensive image simulations. Since the 4A nanotube gives rise to only very weak contrast, great caution must be exercised in establishing the identification. When the 4A nanotube resides inside a multiwalled carbon nanotube, the electron microscope image contrast bears clear signature of its presence, which is indicated by the fading image contrast towards the center of the nanotube. The electron microscopic imaging of single-walled carbon nanotubes of 4A diameter will also be discussed.
Dr. Yuwei Fan
Max Plank Institute for Solid State Research
Heisenbergstr.1
D-70569, Stuttgart
Stuttgart, Baden-Württemberg 70569
Germany
+49-711-6891508 (phone)
+49-711-6891602 (fax)
------------------------------------------------------------
Title: SWNTs modified by selective nanoparticle attachment
Authors: Y.Fan, S.Kooi, U.Schlecht, M.Burghard, K.Kern
Affiliations: Max Plank Institute for Solid State Research
Abstract:
Chemical modification of carbon nanotubes is an active field of research with the goal of tuning the tube’s electrical or optical properties for various applications including ultrasmall electronic devices and chemical sensors. Here we report on two different approaches to modify single-walled carbon nanotubes by the attachment of nanoparticles. In the first case, selenium nanoparticles with sizes on the order of 10nm are selectively formed on the tubes upon treatment with H_{2}Se gas. The second approach involves modifying the tubes with a functional nitrene, created by photochemical activation. Sulfur group within the covalently attached residues can be used to bind different types of pre-formed nanoparticles (eg. Au, CdSe) with sizes in the range of 2-10nm. Both systems were analyzed by AFM, TEM, and EDX.
Dr. Steven E. Kooi
Max Planck Institute for Solid State Research
Heisenberg Str. 1
Stuttgart, D-70569
Germany
49-711-689-1508 (phone)
49-711-689-1602 (fax)
------------------------------------------------------------
Title: Electrochemical Modification of Carbon Nanotubes
Authors: S. Kooi, Y. Fan, U. Schlecht, M. Burghard, K. Kern
Affiliations: Max Planck Institute for Solid State Research
Abstract:
The controlled electrochemical modification of individual single wall carbon nanotubes (and small bundles) on Si/SiO2 substrates is presented. The reduction of a diazonium salt in an aprotic solvent is employed to produce a radical that attacks the nanotube, forming a covalent bond between the nanotube and the dye molecule. In our experiments, the same nanotubes (bundles) were characterized by atomic force microscopy before and after modification. The possibility of using the attached dye molecule to bind a nanocrystal of choice (e.g. Au, Pt, CdSe) is explored. To achieve this goal, appropriate functional groups are produced by further electrochemical reduction of precursor groups on the dye.
p>
Dr. Fumiyuki Nihey
NEC Laboratories
34 Miyukigaoka
Tsukuba, Ibaraki 305-8501
Japan
+81-298-50-1584 (phone)
+81-298-56-6139 (fax)
------------------------------------------------------------
Title: One-Dimensional Localization in Single-Wall Carbon Nanotubes
Authors: F. Nihey, T. Ichihashi, M. Yudasaka, and S. Iijima
Affiliations: NEC Laboratories, ICORP-JST, Meijo Univ.
Abstract:
Single-wall carbon nanotubes (SWNTs) have been intensively studied because of their peculiar electronic properties. SWNTs are either one-dimensional metals or semiconductors, depending on their diameter and chirality. Thus transport measurements on each individual SWNTs are required to reveal their inherent properties. We report one-dimensional localization in an semiconducting SWNT. As-grown SWNTs were directly dispersed on a sapphire substrate in order to reduce the formation of bundles and the creation of damages during the purification processes. Attachment of Ti electrodes to a SWNT followed by heat treatment was carried out to make ohmic contacts. The temperature dependence of the two-terminal resistance showed exp[(T_0/T)^(1/2)] dependence, where T_0=5.4x10^4 K. This temperature dependence implies that one-dimensional variable range hopping dominates this semiconducting SWNT.
Mr. Jesper Nygard
Niels Bohr Institute, Oersted Laboratory
Universitetsparken 5
Copenhagen, DK-2100
Denmark
+45 35320456 (phone)
+45 35320460 (fax)
------------------------------------------------------------
Title: Kondo effect in carbon nanotube quantum dots
Authors: Jesper Nyg{\aa}rd^{1}, David H. Cobden^{2} und Poul Erik Lindelof^{1}
Affiliations: ^{1} Niels Bohr Institute, Ørsted Laboratory, Universitetsparken 5, DK-2100 Copenhagen, Denmark, ^{2} Department of Physics, University of Warwick, Coventry CV4 7AL, UK
Abstract:
For single-wall nanotubes, the electron transport at low temperature is often dominated by Coulomb blockade effects due to tunnel barriers formed between the nanotubes and the attached metallic electrodes. We have obtained low-resistance contacts to single-wall nanotubes, enhancing the higher-order cotunneling processes, and have observed the Kondo effect in such a "quantum dot" [1]. Here, a resonance for transmission exists at low temperature due to the formation of a many-body state involving an unpaired spin on the tube and the conduction electrons in the gold leads. The one-dimensionality of nanotubes makes the effect particularly pronounced, with Kondo temperatures up to 2 K and for large electron number {\it N}. The effect exist only for odd {\it N}, reflecting even-odd alternations due to spindegeneracy. However, at finite magnetic field an effect induced by a singlet-triplet degeneracy is observed for even {\it N}. [1] Nyg{\aa}rd, J., Cobden, D.H., and Lindelof, P.E., Nature {\bf 408}, 342 (2000).
Mr. Mattias Hjort
IFM, Linköping University
Linköpings Universitet
Linköping, SE-581 83
Sweden
+46 13 288962 (phone)
+46 13 132285 (fax)
------------------------------------------------------------
Title: Anderson localization in metallic carbon nanotubes
Authors: M. Hjort and S. Stafström
Affiliations: Linköping University, Sweden
Abstract:
Experimentally, the electron localization length is found to be very large in metallic NT's, regardless of tube chirality. A long localization length is important for the ballistic transport properties of the NT's, and depend crucially on the amount of disorder present in the tube. So far has only disorder induced localization, so called Anderson localization, been studied quantitatively for armchair NT's. We study for the first time also the much more complex chiral NT's, using the transfer matrix method. The electron localization due to diagonal disorder is shown to be independent on chirality and the localization length is in total agreement with the values reported for armchair NT's. Especially, we consider functionalization of the NT's as a diagonal disorder for which the conductance will decrease exponentially with the number of functionalized atoms. This effect may be used in applications where NT's act as sensors. Functionalization in this case also includes atom substitution and gas adsorption, and we have particularly studied the effect of oxygen adsorption.
Dr. Milo S.P. Shaffer
Cambridge University
Dept. Materials Science
Pembroke St.
Cambridge, CB2 3QZ
UK
44 1223 334328 (phone)
44 1223 334567 (fax)
------------------------------------------------------------
Title: Evaluation of the Mechanical Properties of Carbon Nanotubes and Nanofibres under Hydrostatic Pressure by Laser-Raman-Spectroscopy
Authors: Milo Shaffer1, Jan Sandler1, Miguel Montes2, Carole Cooper2, Alexander Kalabushkin3, Karl Schulte4, Alan H. Windle1, Robert J. Young2
Affiliations: 1 Department of Materials Science and Metallurgy, University of Cambridge, UK, 2 Materials Science Centre, UMIST/University of Manchester, UK, 3 Materials for Microelectronics, Technical University Hamburg-Harburg, Germany, 4 Polymer Composites, Technical
Abstract:
Experimental and theoretical results suggest that carbon nanotubes (CNT) and vapour-grown carbon nanofibres (VGCNF) hold promise as reinforcement materials for novel nanocomposites. Although recent progress has been made in testing the mechanical properties of individual carbon nanotubes, a statistically significant experimental analysis of the stiffness of CNT and VGCNF as a function of structure remains a challenging task. In this study the mechanical properties of bulk samples of CNT and VGCNF from different production methods were analysed by Micro-Laser-Raman-Spectroscopy. During hydrostatic compression in a diamond anvil pressure cell the in-plane deformation of the graphitic planes was studied by following the characteristic 1580 cm-1 Raman peak (G band). It has been shown previously for macroscopic high-modulus carbon mesophase pitch fibres that the rate of the G band shift per unit strain is proportional to the Young’s modulus. We demonstrate that the Raman peak shift as a function of hydrostatic pressure can be used to evaluate the elastic mechanical properties of a wide variety of nanoscale carbon materials. In addition, we demonstrate a discontinuity of the elastic response of the nanotubes and nanofibres which we attribute to a reversible flattening and finally an irreversible break down of their structure at high pressures.
Dr. Stefano Bellucci
INFN-LNF
Via E. Fermi 40
P.O. Box 13
Frascati, Roma 00044
Italy
+39-06-9403-2888 (phone)
+39-06-9403-2427 (fax)
------------------------------------------------------------
Title: Chiral-invariant electronic interactions in metallic carbon nanotubes
Authors: S. Bellucci
Affiliations: INFN-Laboratori Nazionali di Frascati
Abstract:
We consider a one-dimensional electron system, suitable for the description of the electronic correlations in a metallic carbon nanotube. Renormalization group methods are used to study the low-energy behavior of the unscreened Coulomb interaction between currents of well-defined chirality. In the limit of a very large number n of subbands we find a strong renormalization of the Fermi velocity, reminiscent of a similar phenomenon in the graphite sheet. For small n or sufficiently low energy, the Luttinger liquid behavior takes over, with a strong wavefunction renormalization leading to a vanishing quasiparticle weight [1]. We apply the approach to study the crossover from two-dimensional to one-dimensional behavior in carbon nanotubes of large radius. Our analysis extends the dimensional crossover from Fermi to Luttinger liquid and the stability of the former [2], even in the case of long-range interactions. Future applications of this approach to explain the proximity-induced superconductivity in carbon nanotubes [3] are briefly discussed. References [1] S. Bellucci, Proc. Sixth Int. Conference on Path Integrals from peV to TeV, Firenze 1998, Eds. R. Casalbuoni et al., (World Scientific 1999), p.363; S. Bellucci and J. Gonzalez, Eur. Phys. J. B 18 (2000) 3; S. Bellucci, Proc. Workshop on Nanotubes and Nanostructures 2000, S. Margherita di Pula (CA), Eds. S. Bellucci, M. De Crescenzi, S. Lagomarsino, Editrice Compositori, Bologna 2001. [2] C. Castellani, C. Di Castro, W. Metzner, Phys. Rev. Lett. 72 (1994) 316. [3] A. Yu. Kasumov et al., Science 284 (1999) 1508; M. Kociak et al., cond-mat/0010220.
Mr. Attila Caglar
University of Bonn, Dept. of Applied Mathematics
Wegelerstr. 6
Bonn, 53115
Germany
+49 228 73 2748 (phone)
+49 228 73 7527 (fax)
------------------------------------------------------------
Title: Reinforcement Mechanisms in Carbon Nanotube Composites
Authors: A. Caglar, M. Griebel, D. W. Brenner, S. J. Frankland
Affiliations: University of Bonn, North Carolina State University
Abstract:
Carbon nanotubes have been proposed as fibers to mechanically reinforce polymers. The load transfer mechanism between the polymer and nanotube has been investigated with classical simulation methods in model polyethylene matrices and epoxy matrices. From molecular dynamics simulation we have estimated that the shear strength of carbon nanotubes in polyethylene is very weak yielding critical lengths (>mm) much longer than is normally physically reasonable for carbon nanotubes. Shear strengths in epoxy matrices are estimated relative to polyethylene. To allow a more direct examination of the mechanical properties, very large-scale simulations of polyethylene-nanotube composites (> 1 million atoms) will be reported where the modeled carbon nanotubes approach an experimentally comparable size. These simulations implement a parallel version of the Brenner potential capable of achieving O(N) complexity with good scaling behavior of up to 512 processors at parallel efficiency of 99% on a CRAY-T3E. A new technique is used to apply tensile stress which varies box shape and size. In addition other reinforcement mechanisms will be considered including the effect of bending the nanotube in the polymer and chemically functionalizing the polymer to the nanotube. Moreover we will present first results with polyethylene composites of nanotubes with encapsulated fullerenes.
Prof. Daniel E Resasco
University of Oklahoma
100 East Boyd St
CEMS
Norman, Oklahoma OK 73019
USA
(405) 325-4307 (phone)
(405) 325-5813 (fax)
------------------------------------------------------------
Title: Highly Selective Catalyst for Synthesis of SWNT by CO disproportionation
Authors: J. E. Herrera, L. Balzano, W. E. Alvarez, D. E. Resasco
Affiliations: University of Oklahoma
Abstract:
The synthesis of single-walled carbon nanotubes (SWNT) by catalytic disproportionation of CO has been systematically investigated. A series of characterization techniques including Raman spectroscopy, TEM and TPO have been employed to characterize the carbon nanotubes. Among a many catalyst formulations investigated, a bimetallic Co-Mo catalyst has been found to be the most effective. A synergistic effect between Co and Mo has been observed. When both metals are simultaneously present, particularly when Mo is in excess, the catalyst is very effective. To understand this synergistic effect, X-ray absorption (EXAFS/XANES), FTIR, and UV/VIS spectroscopies have been used to characterize the state of Co and Mo on the catalysts before and after the production of SWNT. The selectivity of the Co-Mo catalysts towards SWNT production by CO disproportionation strongly depends on the stabilization of Co(II) species before the formation of SWNT begins. This stabilization results from an interaction with Mo and is only effective at low Co/Mo ratios. Under reaction conditions, the Mo oxide species are converted into Mo carbide, thus breaking the interaction and releasing the metallic Co in a state of high dispersion, which is responsible for the production of SWNT.
Dr. Masako Yudasaka
ICORP-JST
34 Miyukigaoka
Tsukuba-shi , Ibarakai 305-8501
Japan
81-298-50-1190 (phone)
81-298-50-1366 (fax)
------------------------------------------------------------
Title: Formation mechanism of single-wall carbon nanotubes and single-wall carbon nanohorns
Authors: M. Yudasaka, Y. Kasuya, D. Kasuya, F. Kokai, K. Takahashi, S. Iijma
Affiliations: ICORP-JST(Tsukuba), NEC (Tsukuba), IRI(Kashiwa), Meijo Univ.(Nagoya), Japan
Abstract:
Formation mechanism of SWNTs is controlled by metal particles with nanometer-sized diameters, probably 1 to 2 nm, and the metals effective to grow SWNTs are good graphitization catalysts, have low solubility in graphite, and the crystallographic orientation on graphite is stable. On the other hand, single-wall carbon nanohorns are formed only from graphite. single-wall carbon nanohorns are formed in an atmosphere where density and temperature of carbon are extremely high, which is realized in the laser plume.
Mr. Olivier Smiljanic
INRS Énergie et Matériaux
1650 bd. Lionel Boulet
Varennes, Québec J3X 1S2
Canada
(450) 929-8237 (phone)
(450) 929-8102 (fax)
------------------------------------------------------------
Title: Gas phase synthesis of SWNT in an atmospheric pressure plasma jet
Authors: Olivier Smiljanic, Barry L. Stansfield, Jean-Pol Dodelet, Alessandra Serventi
Affiliations: INRS-Énergie et Matériaux, Varennes, Québec
Abstract:
We will present a new method for producing single wall nanotubes (SWNT), wherein a gaseous mixture of argon, ethylene and ferrocene is passed through an atmospheric plasma. The plasma dissociates the molecules, and in the exhaust of the plasma flame, the atoms recombine to form SWNT, which are deposited downstream. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy were used to study samples taken from these deposits. The analyses indicate that the deposits are made up of SWNT, with diameters ranging from 1 to 1.5 nm.
Mr. Michael H. Mannsberger
Institut für Materialphysik
Strudlhofgasse 4
Vienna, Vienna 1090
Austria
+43-1-4277-51379 (phone)
+43-1-4277-51375 (fax)
------------------------------------------------------------
Title: COMPARISON OF DIAMETER DISTRIBUTION OF SWCNT BUNDLES AS ANALYZED BY SCANNING PROBE MICROSCOPY AND BY RAMAN MEASUREMENTS
Authors: M.Mannsberger^{1}, H.Kuzmany^{1}, W.Planck^{1}, T.Pichler^{1,2}, A.Grüneis^{1}
Affiliations: ^{1} Institut für Festkörperphysik, Universität Wien, Austria; ^{2} IFW Dresden, Germany
Abstract:
Due to the fabrication process SWCNTs appear mostly as bundles of varying diameters. It has been reported that the use of a strong solvent like DMF (dimethylformamide) in combination with sonication disentangles the nanotube ropes and thus provides individual SWCNTs. We analyzed the distribution of bundle diameter by Raman measurements and by SPM methods before and after sonication. A high dilution of SWCNT bundles and an consequent low area density allowed to get approximate statistics of the diameter distribution of the SWCNT bundles by SPM measurements. As a result of the experiments there were still bundles. Further dilution and sonication did not dissolve these bundles. Work is supported by the FWF projects P12924 and P14146 and the TMR Research Network 'FUNCARS' (HPRN-CT1999-00011) from the EU. T.P. thanks the ÖAW for funding.
Prof. Dong-Ho Kim
Dept. of Physics, Yeungnam University

Daedong, Kyungsan, Kyungpuk 712-249
KOREA
82-2-053-810-2340 (phone)
82-2-053-814-6141 (fax)
------------------------------------------------------------
Title: Direct nano - bridging of carbon nanotube using growth barrier for nanoelectronics : a possible mechanism of selective lateral growth and observation of field effect
Authors: Dong-Ho Kim1, Yun-Hi Lee2, Yoon-Taek Jang2, Chang-Woo Lee1, Chang-Hoon Choi2, Eun-Kyu Kim2, Byeong-Kwon Ju2,Jae-Eun Lee3, Young-Soo Hahn3, Sang-Soo Yoon3, Jin-Koog Shin3, Sung-Tae Kim3
Affiliations: 1 Dept. of Physics, Yeungnam University, Kyungsan, Korea: 2 KIST, Cheongryang P. O. Box 131, Seoul, Korea: 3 LG ELITE, Seoul, Korea
Abstract:
We have fabricated carbon nanotube field-effect transistor of a direct nano-bridged between micro-sized Ni electrodes using conventional photolithography technique. Especially, in this work we introduced a growth barrier of Nb metal or insulating layer on the top of the catalytic metal to prevent the growth of CNW from vertical direction to the substrate. As a result, CNTs were selectively grown between lateral sides of the Ni electrodes with pre-defined Nb external terminals. We have demonstrated the ability of this three thermal structure with back gate to provide field effect of conductance modulation ability of 3-4 orders of magnitude as a function of gate voltage at room temperature. This is the first report on the field effect of the directly bridged CNT-FET with catalytic metal electrodes. We ensure that this will greatly simplify fabrication process so that a large number of nano-electronic devices can be formed by combining cost-effective CVD method at low temperature with a commercially available 1.2 micrometer MOS process.
Dr. Alexis Baratoff
Institute of Physics
University of Basel
Klingelbergstr. 82
Basel, 4056
Switzerland
+4161 267 3726 (phone)
+4161 267 3784 (fax)
------------------------------------------------------------
Title: CVD grown Carbon Nanotube Tips for Atomic Force Microscopy
Authors: V. Barwich, R. Bennewitz, A. Baratoff and E. Meyer
Affiliations: Institute of Physics, University of Basel, Klingelbergstr. 82, 4056 Basel, Switzerland
Abstract:
Small-diameter, high-aspect ratio, stiff, but highly flexible carbon nanotubes (CNT) are well-suited for Atomic Force Microscopy (AFM). We can grow thin individual CNT on the pyramidal tip of a microfabricated silicon cantilever. Catalyst particles (alumina enclosed by iron and molybdenum or a thin film of iron) are first deposited and then subjected to CVD. The optimal parameters for growing thin, straight CNT are about 750°C, 10 min and 10:700:1050 cm3/min for a ethylene-hydrogen-argon mixture. Suitable protruding CNT were characterized by SEM, then shortened to less than 200 nm by electrical etching in order to reduce the lateral thermal vibration amplitude. Images of ionic crystal surfaces have been recorded in UHV in the non-contact mode. Resonance frequency vs. distance curves reveal the desired reduction of long-range forces.
Dr. Christophe LAURENT
Universite Paul-Sabatier
CIRIMAT, UMR CNRS 5085 / LCMIE
Bat. 2R1, Universite Paul-Sabatier
Toulouse cedex 4, 31062
France
+33 561 55 61 22 (phone)
+33 561 55 61 63 (fax)
------------------------------------------------------------
Title: Oxidation in air of CCVD and laser-ablation carbon nanotubes
Authors: A. Peigney, E. Hallberg, R. Bacsa, Ch. Laurent
Affiliations: CIRIMAT / LCMIE, UMR 5085, Université Paul Sabatier, Toulouse, France
Abstract:
The aims of the study of the oxidation in air of CNTs samples are to characterize the samples on a macroscopical scale, by detection of the phases that may be present (SWNTs, MWNTs, nanocapsules, …), to purify the sample by selective oxidation and to investigate the opening of CNTs tips. Laser-ablation (Tubes@Rice) and CCVD (the authors laboratory) specimens are studied by DTA and TGA/DTG in isothermal and non-isothermal modes. Their specific surface area is measured. Selected specimens are observed by HREM.. The laser-ablation sample is oxidized in two steps (355 and 450°C) corresponding to the amorphous carbon and residual surfactant and to the SWNTs bundles, respectively. For the CCVD CNTs, there is a competition between the oxidation of SWNTs and that of outer walls of DWNTS and TWNTs. In the as-prepared CNTs-Co-MgO powders, some CNTs tips are opened, then the outer wall of DWNTs is oxidized (up to 420-440°C), leading to an increase in the proportion of SWNTs. In the corresponding extracted CNTs, SWNTs are oxidized below 400°C, then the DWNTs and TWNTs are opened and eventually oxidized. The difference could arise from the more compact nature of the extracted sample. The interpretation of the DTA patterns will be discussed.
Mr. Joerg Engstler
Karl-Franzens-University
Department of Chemistry/Inorganic Chemistry
Schubertstrasse 1
Graz, Steiermark 8010
Austria
+43-316-380-5293 (phone)
+43-316-380-9835 (fax)
------------------------------------------------------------
Title: MOCVD Approach to Aligned Isolated Carbon Nanotubes. Materials for Cold Cathode Field Emitters
Authors: J. J. Schneider^{1,*}, J. Engstler^{1}, G. Mueller^{2}, B. Guenther^{2}
Affiliations: ^{1} Karl-Franzens-University, Department of Chemistry/Inorganic Chemistry, Schubertstrasse 1, 8010 Graz, Austria. ^{2} University of Wuppertal, Department of Physics, Gaussstrasse 20, 42119 Wuppertal, Germany.
Abstract:
Carbon nanotubes (CNTs) are promissing materials for cold cathode field emitters.^{1} Parallel alignment over large areas has to be achieved to reach this goal. We have studied organic as well as organometallic catalytically driven template based thermal CVD approaches to achieve this goal.^{2,3} These Approaches are attractive due the single source strategy used wich employs the use of low cost organometallic complexes containing both the metal as well as the carbon atoms.^{4} Geometric structuring of the alumina embedded CNTs can be achieved either by a laser structuring process or by simple ink jet catalyst impregnation.^{5} By using organometallic precursors a single source strategy is possible wich even allows to incorporate metals within the CNTs. In situ visualisation of the individual field emission sites was achieved by field emission spectroscopy. [1] P. Calvert, {\it Potential Applications of Carbon Nanotubes}, in {\it "Carbon Nanotubes, Preparation and Properties"} (T.W. Ebbesen, ed.), CRC Press, Boca Raton, USA, {\bf 1997}. [2] G. Che, B.B. Lakshmi, C.R. Martin, E.R. Fisher, {\it Chem. Mater.} {\bf 1998}, {\it 10}, 260. [3] J.J. Schneider, G.L. Hornyak,et al., {\it Nanostr. Mater.} {\bf 1999}, {\it 12}, 83. [4] C.N.R. Rao et al.,{\it Chem. Commun.} {\bf 1998}, 1525. [5] J.J. Schneider, J. Engstler et al., {\it Chem. Eur. J} {\bf 2001} {\it in press}.
Dr. Yun-Hi Lee
Korea Institute of Science & Technology(KIST)
39-1, Hawolgokdong
Sungbuk-gu, Seoul 139-791
KOREA
82-2-958-5772 (phone)
82-2-958-5692 (fax)
------------------------------------------------------------
Title: Temperature dependence of field effect function of a direct bridged CNT between ferromagnetic electrodes:Ni as both catalyst and contact electrode
Authors: Yun-Hi Lee1, Dong-Ho Kim2, Yoon-Taek Jang1,Chang-Woo Lee2, Chang-Hoon Choi1, Eun-Kyu Kim1, Byeong-Kwon Ju1, Jae-Eun Lee3, Young-Soo Hahn3, Sang-soo Yoon3, Jin- Koog Shin3, Sung-Tae Kim3,
Affiliations: 1 KIST, Seoul, Korea : 2 Dept. of Physics, Kyungsan, Korea:3 LG Elite, Seoul, Korea
Abstract:
The temperature dependences of the field effect of a direct nano-bridged carbon nanotube (CNT) between micro-sized Ni electrodes were studied in the range of 100-300 K under back-gate biasing. CNTs were selectively grown between the lateral sides of the Ni electrodes with pre-defined Nb external terminals. The temperature dependence of two-terminal resistance showed a thermal activation at high temperatures in all samples measured. At the room temperature linear resistance of Ni-CNT-Ni structure showing field effect function was about 5 megaohm. The normalized resistance R(T)/ R(300K) increases three or five orders of magnitude from 5megaohm to gigaohm range as the temperature is lowered from 300 to 80 K, showing nearly insulating transition. The differential conductance versus bias voltage spectrum showed energy gap (E) of ~1.4 eV at 100 K and this value corresponds to the outer diameter d of about 1.6 nm from the relation of energy gap(E) ~ 1/d. Considering Eg =1.8 eV for a single wall nanotube with diameter of 1.3 nm, the estimated value is reasonable. We also observed an interesting temperature and time dependence of device characteristics and will discuss their implication in terms of intrinsic and extrinsic properties of the devices.
Prof. Leonid A Chernozatonskii
Institute of Biochemical Physics Russian Academy of Sciences
4 Kosygin St
Moscow, 119991
Russia
7-095-1378347 (phone)
7-095-1374101 (fax)
------------------------------------------------------------
Title: POLYMER FORMS OF SINGLE WALL NANOTUBES
Authors: Leonid Chernozatonskii a, Madhu Menon b
Affiliations: a Department of Material Researches, Institute of Biochemical Physics, Russian Academy of Sciences, Moscow 117977, Russia
Abstract:
A number of high-pressure-high-temperature structures of the SWNT structures are considered. Mechanism of polymerization for both doubly crossed (n,m) nanotubes and two parallel (n,n) and (n,0) SWNT’s by means of cycloaddition process is discussed. Coupling of two neighbor nanotubes is energetically favorably under the “zipper” scheme. After readjustments of (2+2) cycloaddition of some atom pairs, step by step polymerization takes place along line between the tubes. Role of hydrogenation in the process of coupling and depolymerization of SWNT is discussed. The “zipper” mechanism is used to explain the following: 1) formation of zeolite structures [1], 2) transformation of molecular coupled nanotube rope into graphite needle under high pressure treatment [2]; 3) formation of double diameter nanotubes under high temperature and light atom flow treatment [3]. We have modeled some examples of polymer SWNT rope transformations using (n,n) and (n,0) carbon nanotubes with n=5-12. New nanotube polymer crystals are computed by using molecular mechanics [1] and a generalized tight-binding molecular-dynamic (GTBMD) method [4]. Energetic characteristics show high stability for all these structures. Furthermore, electronic band structures of such SWNT polymers show changing of electronic properties of original SWNT ropes from narrow semiconductor to dielectric: (12,12) NT structure with (2+2) cycloaddition [sp3/sp2 =1/4]; semiconductor crystals of (6,6) NT structure with (2+2) cycloaddition [sp3/sp2 =1], and (9,0) NT structure with (2+4) cycloaddition [sp3/sp2 =1/2]; high dielectric gap crystals of (6, 0) and (6, 6) NT structures with all sp3 atoms. Some of considered structures have good agreement with experiments [3, 5]). This work was supported by “Atomic Clusters and Fullerenes” Russian Government Program, Russian Fundamental Fund of Investigation and NSF. 1. L.A. Chernozatonskii. Chem.Phys.Lett. 297 (1998) 257. 2. E.D. Obraztsova et al. in Elecrtonic Properties of Novel Materials. Proc. WINTERSCHOOL’99, Kirshberg. AIP Conf.Proc.486, N.Y. 1999. 3. P. Nikolaev, et al. Chem.Phys.Lett. 266 (1998) 322; S. Bonnamy et al. Proc. Carbon Conf., Tokyo, Nov.1998 4. M. Menon, E.Richter, K.R.Subbaswamy, Phys.Rev. B 57 (1998) 4063 5. M. Popov, M. Kyotani, Y. Koga et al. Phys. Rev. B (2001, in press)
Prof. Nobukata NAGASAWA
Department of Physics, Adv.School of Science, Univ. of Tokyo
7-3-1,Hongo,Bunkyo-ku
Tokyo, 113-0032
Japan
+81-3-5841-4181 (phone)
+81-3-5842-4230 (fax)
------------------------------------------------------------
Title: Visible Emissions of Single-Walled Carbon Nanotubes Formed in Zeolite Crystals
Authors: N. Nagasawa 1, I. Kudryashov 2, and Z. K. Tang 3
Affiliations: 1)University of Tokyo, Japan?2) Tokyo Instruments Inc.Japan, and 3) Hong Kong Univ. of Science and Technology, China
Abstract:
Mono-sized, aligned and single-walled carbon nanotubes (SWCNs) of about 0.4 nm diameter are formed inside micro-channel array of a zeolite single crystal. Since they are forced to align along c-axis of the crystal, they show strong polarization anisotropy in the optical absorption from near infrared to visible region [1]. The crystal is opaque in the polarization configuration E//c , but is almost transparent in E?c , where E is the electric field vector of the incident light. We have found strong emissions in visible regions under the monochromatic photo-excitations at room temperature. They showed strong polarization correlation with the absorption spectra. To know the spatial distribution of the emission sources and the origins, 3D micro-tomographic measurements are performed using the "Nanofinder" of nano-scale spatial resolution [2]. In this paper, we discuss these polarization characteristics in view of the selection rules of relevant optical transitions on the basis of the band calculation obtained by the LDA. [1] Z.K.Tang, Z.M.Li, G.D.Li, N.Wang, H.J.Li and C.T.Chan, to be published in the Proceedings of Inter. Symposium on Network Materials: Fullerenes, Nanotubes, and Related Systems, ISNM2001, Kamakura, Japan. [2] N.Nagasawa, I.Kudryashov, S.Tsuda, and Z.K.Tang, to be published in the Proceedings of ISNM2001.
Dr. Masahito Sano
JST
2432 Aikawa
Kurume, Fukuoka 839-0861
Japan
+81-942-39-9011 (phone)
+81-942-39-9012 (fax)
------------------------------------------------------------
Title: Nanoring formation by ring-closure reactions of carbon nanotubes
Authors: M. Sano, A. Kamino, J. Okamura, S. Shinkai
Affiliations: Chemotransfiguration Project - JST
Abstract:
Ring-closure reactions were applied onto single-walled carbon nanotubes in solution so that one end of a tube reacted with another end of its own. From the size distribution of nanorings, elastic properties in solution are analyzed.
Ms. priscilla simonis
University of Namur
LASMOS laboratory
rue de bruxelles, 61
Namur, 5000
Belgium
+32 81 72 47 12 (phone)
+32 81 72 47 07 (fax)
------------------------------------------------------------
Title: STM STUDY OF A GRAIN BOUNDARY IN GRAPHITE
Authors: P. Simonis^{1}, C. Goffaux^{2}, V. Meunier^{3}, L.P. Biro^{4} and P. A. Thiry^{1}
Affiliations: ^{1} Laboratoire de spectroscopie moléculaire de surface, University of Namur, B-5000 Namur, Belgium, ^{2} laboratoire de physique du solide, University of Namur, B-5000 Namur, Belgium, ^{3} Research Institute for Technical Physics and Materials Sciences, H-1525 Budapest, Hungary, ^{4} see below add. information
Abstract:
In a STM investigation of HOPG, an intriguing coiled structure was observed near a grain boundary. The atomic resolution obtained on this structure revealed a regular linear pattern parallel to the grain boundary. Theoretical simulations were elaborated in order to explain this characteristic pattern. They suggested that it could fingerprint a line of pentagon-heptagon couples resulting from Stone-Wales deformations of the hexagonal lattice close to the grain boundary.
Prof. Kazuyuki Watanabe
Science University of Tokyo
1-3 Kagurazaka, Shinjuku
Tokyo, 162-8601
Japan
+81-3-3260-4665 (phone)
+81-3-3260-4665 (fax)
------------------------------------------------------------
Title: Application of Partitioned Real-Space Density Functional Method to Field Evaporation from Carbon Nanotubes
Authors: N. Nakaoka, K. Tada, and K. Watanabe
Affiliations: Department of Physics, Science University of Tokyo
Abstract:
Recently, some carbon cluster ions have been selectively observed by field evaporation from carbon nanotubes.^{1)} When the electric field (the direction is opposite to that of electron field emission) is applied to the carbon nanotube tip, a carbon atom or cluster of the tip are positively ionized and evaporated toward the vacuum along the potential slope caused by the electric field. It has been impossible from first-principles calculations based on the density functional theory (DFT) to study the field evaporation under bias voltage (unequal Fermi energies) and zero electric current, because the DFT seeks the global ground state with one Fermi energy accompanying artificial electron transfer. To overcome the essential difficulty of the DFT above, we have developed a new partitioned real-space density functional (PRDF) method ^{2)} which determines the electronic states and two Fermi energies of bielectrode under bias voltage self-consistently. We applied the PRDF method to field evaporation from single-walled carbon nanotubes. We determine the potential energy curve for evaporation of C_{5}^{+} cluster ion and found a drastic decrease in the activation barrier for evaporation in an electric field of 3V/\AA. The stable structure of the smallest fullerene ion, C_{20}^{+}, has been obtained. The details of the mechanism of field evaporation will be discussed. References 1)K. Hata, et al., Chem. Phys. Lett. 308, 343 (1999). 2)N. Nakaoka, et al., Phy. Rev. Lett. 86, 540 (2001).
Dr. Maik Liebau
Infineon Technologies
CPR NP
Otto-Hahn-Ring 6
Munich, Bavaria D-81739
Germany
+49-89-23457433 (phone)
+49-89-23447069 (fax)
------------------------------------------------------------
Title: Multiwall Carbon Nanotubes Grown on Metallic Substrates
Authors: F. Kreupl, A. Graham, E. Unger, M. Liebau, W. Hönlein
Affiliations: Infineon Technologies AG, Corporate Research, 81739 Munich
Abstract:
Chemical vapour deposition is a well-known technique used throughout the semiconductor industry and is therefore the method of choice when it comes to an implementation of carbon nanotubes (CNTs) in a process flow. Whereas CNTs grown on oxidic substrates are well established, much less efforts and success has been reported on CNTs grown on metallic surfaces. This is where our recent studies are focusing on. In order to exploit the high electrical performance of CNTs, they have to be connected at both sides with highly conductive, i. e. metallic contacts. Besides the quality of the grown CNTs it is also very important that they can be grown on metallic surfaces giving inherently a good contact resistance due to the close contact to almost all layers of a multi-wall CNT. We will report on the compatibility of various catalyst/metallic substrate combinations, which are producing multi-wall CNTs of high quality.
Dr. Christophe LAURENT
Universite Paul-Sabatier / CNRS
CIRIMAT, UMR CNRS 5085 / LCMIE
Bat. 2R1, Universite Paul-Sabatier
Toulouse cedex 4, 31062
France
+33 561 55 61 22 (phone)
+33 561 55 61 63 (fax)
------------------------------------------------------------
Title: Synthesis of carbon nanotubes by CCVD
Authors: S. Rul, A. Peigney, Ch. Laurent, A. Rousset
Affiliations: CIRIMAT / LCMIE, UMR 5085, Université Paul Sabatier, Toulouse, France
Abstract:
The reduction of a Mg0.9Co0.1O oxide solid solution at 1000°C in H2/CH4 atmosphere produces cobalt particles small enough to catalyze the formation of SWNTs and thin MWNTs (mostly 2, 3 walls). The so-obtained CNTs-Co-MgO powders are treated in dilute HCl in order to dissolve MgO and most of the cobalt particles. The composite powders and the extracted CNTs are studied by several techniques including scanning and transmission electron microscopy, Raman spectroscopy and a macroscopical method involving specific surface area measurements and elemental carbon analysis. It is the combination of the appropriate cobalt content, reduction temperature and CH4 content that allows to control the formation of the cobalt nanoparticles so as to avoid their exaggerate growth and subsequent encapsulation by graphene layers. It is shown that increasing the CH4 content in the H2/CH4 atmosphere from 18 to 50 mol. % allows a twofold increase of the quantity of CNTs without important modifications of their characteristics. 45-55% of the CNTs are SWNTs, 30-40% are DWNTs, and the average inner diameter is close to 1.9 nm. The purity and the reactivity in air of the materials will be discussed.
Mr. Glenn Wright
GMA Industries, Inc.
20 Ridgely Avenue
Suite 301
Annapolis, MD 21401
USA
01-410-267-6600 (phone)
01-410-267-6602 (fax)
------------------------------------------------------------
Title: Nanotube Sensors for the Detection of Failures within Integrated Circuits
Authors: Glenn Wright, Marek Zgol, Susanna Keeton
Affiliations: GMA Industries, Inc.
Abstract:
This abstract describes original research and development in the use of nanotube-based chemical and electronic sensors as embedded test equipment within the architecture of integrated circuits (ICs) to detect failures that may affect IC reliability and performance. This R&D being performed by the Nanoteknology Division of GMA Industries, Inc., focuses on the monitoring of electrical and chemical activity within the IC to provide a fast, accurate, and inexpensive identification of failures. Results are presented from the development of two nanotube-based devices: a metal migration sensor and a nanotube rectifier diode. The metal migration sensor uses the properties of carbon nanotube conductivity to detect a small change in current density caused by an increased area in contact with the metal, while the overlapping of two semiconducting nanotubes creates the rectifier diode. We will describe our methods for the chemical modification and tailoring of nanotube properties to fulfill our application requirements, convey any experimental results achieved to date, and discuss lessons learned in the process.
Dr. Holger F Bettinger
Lehrstuhl für Organische Chemie II
Ruhr-Universität Bochum
Universitätsstr. 150
Bochum, 44780
Germany
+49-234-322-4529 (phone)
+49-234-321-4353 (fax)
------------------------------------------------------------
Title: Properties of fluorinated single-walled carbon nanotubes as derived from density functional computations
Authors: Holger F. Bettinger, Konstantin N. Kudin, Gustavo E. Scuseria
Affiliations: Department of Chemistry MS-60, and Center for Nanoscale Science and Technology, Rice University, PO Box 1892, Houston, TX 77251-1892, USA.
Abstract:
Fluorination of single-walled carbon nanotubes at elevated temperatures results in the production of tubular species with a stoichiometry close to C2F. We here present the electronic and geometric structures of fluorinated single-walled nanotubes (F-SWNT) as obtained using density functional theory in conjunction with all-electron Gaussian basis sets under periodic boundary conditions. We find that the fluorine atoms are bound covalently to the tube surface, and that the band structure of the F-SWNT depends decisively on the distribution of the fluorine atoms. For certain fluorination patterns, metallic properties of the F-SWNT are expected. The geometries of the tubes distort significantly upon fluorination, e.g., resulting in pentagonal, tetragonal or trigonal structures for (5,5), (4,4), and (3,3) F-SWNT's, respectively. The mean C-F bond dissociation energy (BDE) increases with decreasing tube diameters; an interpretation of this behaviour is given. Comparing the C-F BDE with that of well known carbon-fluorine compounds indicates that the C-F bonds in small diameter F-SWNT are about as strong as those in graphite fluoride (CF)_{x}. Finally, the ^{19}F nuclear magnetic properties of F-SWNT and (CF)_{x} are compared and discussed.
Mr. Sunghwan JIN
samsung advanced institute of technology
display lab.
P.O. Box 111,
Suwon, 440-600
korea
+82-31-280-8236 (phone)
+82-31-280-9349 (fax)
------------------------------------------------------------
Title: Field emission energy distribution for an undergated triode CNT-FED
Authors: Sunghwan Jin, Whikun Yi, SeGi Yu, Jungho Kang, Taewon Jeong, Jeonghee Lee, Jungna Heo, Yongsoo Choi, Wonseok Kim, Y.H. Lee, and J.M. Kim
Affiliations: samsung advanced institute of technology
Abstract:
We have measured I–V characteristics and field emission energy distribution (FEED) for an undergate-type triode carbon nanotubes-field emission display (CNT-FED), which has gate electrodes with an insulating layer located under the cathode electrodes. The emitters of an undergated CNT-FED were fabricated by the printing method with CNT paste, which was mostly consisted of glass powders. For the diode emission, the FEED peaks (E-EF) shift with 67 meV/V, and ? was found to be 26,054 ?-1 from the I-V measurement. On the while, peaks for the triode emission shift with 270 ~ 500 meV/V because of the strong electric field induced by the gate. We also observed subpeaks below the main peaks, which may be occurred from the existence of glass surrounding CNTs. The FWHM of peaks for diode and triode emission were broader than those reported by others, i.e., 0.7 ~ 1.9 eV, which may be caused by field emission from various geometry of CNTs. In summary, we measured the FEED of the undergated CNT-FED for the first time, and the FEED peaks shift as the applied voltage increased, which supports the energy band bending in CNTs
Prof. Juan J. Palacios
Universidad de Alicante
Dpto. de Fisica Aplicada
Facultad de Ciencias
San Vicente del Raspeig, Alicante 03690
Spain
+34 965909630 (phone)
+34 965903464 (fax)
------------------------------------------------------------
Title: Electrical transport in nanotubes with realistic contacts: An ab-initio study
Authors: J. J. Palacios, A. J. Perez-Jimenez, E. Louis, and J. A. Verges
Affiliations: Universidad de Alicante and ICMM
Abstract:
We present an ab-initio study of the electrical transport properties of fullerenes and short nanotubes contacted to metallic electrodes. The part of the electrodes that is close to the contact with the molecules, is described at the atomic level and treated at the same level of approximation as the nanotubes. Far away from the contacts, where the details are unimportant, the electrodes are described by Bethe lattices. This allows us to estimate the contribution of the semiinfinite parts of the system in a simple manner. We show that a good description of the charge transfer at the contact region is essential to obtain the correct band structure and to understand the transport properties of these molecules in actual experiments.
Dr. Harald Goering
Bundesanstalt für Materialforschung und -prüfung
Unter den Eichen 87
Berlin, D-12205
Germany
+49-30-81 04 33 98 (phone)
+49-30-81 04 16 37 (fax)
------------------------------------------------------------
Title: Synthesis and characterization of single-walled carbon nanotubes/polymer network composites
Authors: H. Goering, H.-E. Maneck, U. Knoll, S. Gajewski, K.-W. Brzezinka, R. Mach, H.-D. Klotz, A. Schönhals, J.F. Friedrich
Affiliations:
Abstract:
Blending of a flexible polymer matrix and a nanoscopic rod-like filler is an important method to improve the mechanical and electrical properties of polymer materials. For a mechanical reinforcement the effect is increased with the concentration, the aspect ratio and the modulus of the filler. However, the improved electrical conductivity of the systems needs the percolation of the filler particles. Considering both aspects carbon nanotubes are an ideal nanoscopic material for blending polymers. Single-walled carbon nanotubes (SWNT) used in this work were synthesized by dc arc discharge process using metal-doped graphite anode (Ni/Y=4/1 at.%). The as grown SWNTs have been purified by chemical methods using HCl to remove catalyst particles followed by oxidation with HNO3. This purification process was controlled by TGA, SEM, TEM and Raman scattering. The SWNTs were dispersed in the monomer component before the polymer network was formed. The dispersion process was assisted by surfactants. The synthesized SWNT/epoxy resin and SWNT/polyurethane network composites were characterized by TEM, SEM, DMA, Raman scattering, and dielectric relaxation spectroscopy. For establishing structure-properties relationship, specific mechanical and electrical parameters are discussed. As expected, concentrations of SWNT smaller than 1 wt.% influence strongly these properties of the polymer matrix as well as the structure of the networks.
Mr. Jan Sandler
University of Cambridge
Department of Materials Science and Metallurgy
Pembroke Street
Cambridge, CB2 3QZ
United Kingdom
0044 1223 334 335 (phone)
0044 1223 334 567 (fax)
------------------------------------------------------------
Title: Carbon-Nanofibre-filled thermoplastic composites
Authors: Jan Sandler1, Milo Shaffer1, Jacek Nastalczyk2, Christian Keun2,
Affiliations: 1 Department of Materials Science and Metallurgy, University of Cambridge, UK
Abstract:
Experimental and theoretical results suggest that carbon nanofibres (CNF) hold promise as reinforcement materials for novel nanocomposites. We have investigated a range of composite systems using nanofibres of differing structure and diameter in a number of representative thermoplastic matrices, including commodity and high performance resins. We have particularly examined mechanical and electrical properties of the nanocomposite materials and, as with conventional composites, have found that the critical factors influencing composite performance are quality of the nanofiller, the nature of the filler dispersion, and the strength of the filler-matrix interface. We have achieved a high degree of dispersion in all matrices, using an intensive shear mixing protocol in conventional thermoplastic processing equipment, and have fabricated standard test samples by injection moulding. The degree of dispersion can be monitored directly by electron microscopy and by analysis of the dielectric response. Microscopy, mechanical testing, and micro-Raman studies have shown that the interfaces between untreated nanofibres and the thermoplastic matrices tested are very weak and little or no load is transferred to the filler. Use of a pre-oxidation treatment, however, can increase the interfacial bond strength, leading to an increase in stiffness and yield strength for certain systems.
Dr. Philippe Roussignol
Laboratoire de Physique de la Matière Condensée
Ecole Normale Supérieure
24 rue Lhomond
Paris, 75005
France
33 1 44 32 25 57 (phone)
33 1 44 32 38 40 (fax)
------------------------------------------------------------
Title: Light Emission from Carbon Nanotubes
Authors: J.S Lauret^{1,2}, C. Delalande^{1}, Ph. Roussignol^{1}, A. Filoramo^{2}, J.N. Patillon^{2}, A.M. Bonnot^{3}, M. Chaumont^{3}, T. Fournier^{4}, L. Pontonnier^{5}, S. Roche^{6}, S. Landis^{6}
Affiliations: ^{1}LPMC de l' ENS, 24 rue Lhomond 75005 Paris, France.^{2} Centre de Recherche Motorola –Paris, 91193 Gif , France.^{3} CNRS, LEPES, BP 166, 38042 Grenoble Cedex 9, France. ^{4} CNRS, CRTBT, BP 166, 38042 Grenoble Cedex 9, France.^{5} CNRS, LC, BP 166, 3
Abstract:
1 LPMC, Ecole Normale Supétieure, 24 rue Lhomond 75005 Paris, France 2 Centre de Recherche Motorola –Paris,Commune de Saint Aubin, 91193 Gif sur Yvette, France 3 CNRS, LEPES, BP 166, 38042 Grenoble Cedex 9, France. 4 CNRS, CRTBT, BP 166, 38042 Grenoble Cedex 9, France. 5 CNRS, LC, BP 166, 38042 Grenoble Cedex 9, France. 6 DRFMC/SPSMS-CEA, 38042 Grenoble Cedex 9, France Carbon nanotubes have been synthesised on Si substrates by use of Hot Filament assisted CVD (HFCVD) technique. Typical synthesis parameters were a 5 - 15 vol. % methane proportion in hydrogen, a 1800 – 2000 °C filament temperature and a 700 - 900 °C substrate temperature. The growth morphology observed with SEM and crystallographic structure determined by TEM demonstrated that depending on substrate preparation and synthesis conditions MWNT or SWNT have been prepared. Thanks to Raman spectroscopy measurements undertaken for different laser radiations (633nm, 514 nm and 458 nm), the presence of very well crystallized and pure SWNT has been demonstrated. Moreover, emission lines due to recombination of electron-hole pairs at different Van Hove singularities have been recorded in semiconducting SWNT. This suggests significant potentiality of these novel materials for optoelectronics applications.
Mr. Harry C Shaw
NASA/Goddard Space Flight Center
Component Technology and Radiation Effects Branch
Code 562, Bldg 6, S-18
Greenbelt, MD 20771
US
301-286-6616 (phone)
301-286-1695 (fax)
------------------------------------------------------------
Title: Nanotechnology Initiative at Goddard Space Flight Center - Fabrication, Analysis, Applications, Partners, Future Directions
Authors: J. Benavides, H. Leidecker, H. Shaw^{1},D.M. Preston^{2}
Affiliations: ^{1} NASA/Goddard Space Flight Center, ^{2} DuPont Corporate Center for Analytical Sciences
Abstract:
The GSFC Nanotechnology initiative is a relatively new effort to rapidly advance the use of nanotechnology in space applications. The key thrusts at GSFC are: 1) the development of inexpensive tools and solutions for carbon nanotube synthesis and purification, 2) development of high impact space applications. We will discuss our techniques and summarize some of the key analytical results from our partners, including some new fluorescence spectroscopy results. We will discuss nanotube applications GSFC is currently exploring and discuss intended research directions.
Dr. Young-Soo Han
LG Electronics Institute of Technology
16 Woomyeon-dong
Seocho-gu
Seoul , 137-724
Korea
+82-2-526-4921 (phone)
+82-2-526-4922 (fax)
------------------------------------------------------------
Title: Technology of Forming the CNT-Bridge on Silicon Substrate for the Electronic Device Applications
Authors: Young-Soo Han, Min-Jae Jung, Jae-Eun Lee, Sang-Soo Yoon, Jin-Koog Shin, Sung-Tae Kim, Yun-Hee Lee
Affiliations: LG Electronics Institute of Technology
Abstract:
In order to increase the possibility in the application of carbon nanotube (CNT) to electronic devices, the CNT synthetic process must be based on Si semiconductor process, and have some compatibility with Si technology. So we made catalytic patterns with Ni on the SiO_{2}/Si substrate by photo-lithography and attempted the selective lateral growth of carbon nanotube by thermal CVD process. The catalytic patterns were designed in form of line-to-line or dot-to-dot with various spacing and shape. For a vertical growth barrier as well as an electrode we deposited a metal (Au, Nb, Mo etc.) layer on the patterns. We could successfully demonstrate the parallel(or lateral) direct growth of CNT and confirm the robust contact between CNT and catalyst by FESEM images. Typical CNT diameters are in the range of 10 to 20 nanometer. We observed that the diameter and morphology were strongly dependent on the acetylene gas flow rate, fraction in diluted reaction gas and temperature. In addition, we also measured the electronic transport properties of CNT bridge formed between catalytic patterns. Its resistance is changed from several hundreds kilo-ohms to several tens mega-ohms as temperature decreases.
Dr. Sang-Soo Yoon
LG Electronics Institute of Technology
16 Woomyeon-dong
Seocho-gu
Seoul, 137-724
Korea, Republic of
82-2-526-4367 (phone)
82-2-526-4922 (fax)
------------------------------------------------------------
Title: Gate dependency of FET made with laterally grown CNT under Si-based process
Authors: Sang-Soo Yoon, Jae-Eun Lee, Young-Soo Han, Min-Jae Jung, Jong-Moo Lee, Jin-Koog Shin, Sung-Tae Kim, Yun-Hee Lee, Dong-Ho Kim
Affiliations: LG Electronics Institute of Technology, Korea Institute of Science and Technology, Yeongnam Univ.
Abstract:
For the industrial application, not only to make electronic devices using carbon nanotube - CNT, but also to manufacture them are important. The CNT synthetic process needs to have some compatibility with Si technology in order to manufacture the CNT devices. So we made catalytic patterns with Ni on the SiO_{2}/Si substrate by photo-lithography and deposited Nb as a electrode. The lateral (or parallel) growth of CNT is successully demonstrated by using Thermal-CVD. We measured the RT curve. The resistance of CNT device was changed from several hundreds kilo ohms to several tens megaohms as temperature decreases. It looks like semicoducting behavior. >From I-V curve, we observed strong gate dependency. We fabricated CNT - Field Effect Transistor. Transport in the CNTs is dominated by holes. Using the gate electrode, the conductance would be modulated by more than 2 - 3 orders of a magnitude. We looked into the contact resistance of our device, which is composed of 'Nb-Ni-CNT-Ni-Nb' in series. Also, we investigated the gate dependence of devices with curved CNT as well as those with linear CNT. We will use several kinds of material - for example, Mo, Co, Pd, and Au - as catalysts or electrodes and investigate the gate dependence on the catalysts and the electrode materials.
Dr. Akinobu Kanda
Institute of Physics, University of Tsukuba
1-1-1
Tennodai
Tsukuba, Ibaraki 305-8571
Japan
+81-298-53-4345 (phone)
+81-298-53-4216 (fax)
------------------------------------------------------------
Title: Barrier formation in electrical contacts between metal and multi-wall carbon nanotube
Authors: A. Kanda^{1,2}, K. Tsukagoshi^{3}, Y. Ootuka^{1,2}, and Y. Aoyagi^{3}
Affiliations: ^{1} Institute of Physics, University of Tsukuba, Japan, ^{2} CREST, Japan Science and Technology Corporation, Japan, ^{3} The Institute of Physical and Chemical Research (RIKEN), Japan
Abstract:
For the application of carbon nanotubes to molecular electronic devices, it is very important to control the contact resistance between metal and a nanotube. In order to get information on the origin of contact resistance, we have studied material dependence of the electrical transport in metal/MWNT/metal structure in metal-on-tube configuration. When the metal was Ti, the room temperature resistance ranged from 28 k\{Omega} to 45 M\{Omega}, and all of the samples cooled to 30mK showed the Coulomb blockade (CB) effect. The total junction capacitance estimated from the CB was proportional to the length of MWNT segments overlapped by Ti electrodes, showing that the tunnel barrier was located in the Ti-MWNT contact. When the metal is Au with the sticking layer of Pt, on the other hand, resistance distribution shifted to a much lower value in comparison with Ti, though the fabrication process was the same. This shows that the contact resistance comes from the mismatch between MWNT and the metal. One possible origin of high contact resistance is oxidation of the metal surface touching the MWNT.
Dr. Raouf O. Loutfy
MER Corporation
7960 S. Kolb Rd.
Tucson, Arizona 85706
USA
520 574 1980 (phone)
520 574 1983 (fax)
------------------------------------------------------------
Title: Hydrogen Adsorption on Different types of Nanotubes
Authors: Dr. M. Ashraf Imam, and Dr. R.O.Loutfy
Affiliations: Naval Research Laboratory & MER Corporation
Abstract:
A key technological barrier to the development of fuel cells, particularly for portable and transportation uses, is the unavailability of a compact, high storage capacity, lightweight and rechargeable hydrogen storage system. The recently discovered Carbon Nanotubes are now the fastest-growing subfield of carbon materials research. The unique structure, physical and chemical properties of these recently discovered fullerene nanotubes materials have lead to the investigation of these materials for many applications. One potential application that has received significant research effort is that of hydrogen storage in these unique carbon structures. The method of production and associated characteristics of different types of carbon nanotubes (the different types of Single-walled, arc multi-walled, CVD random multi-walled CVD aligned multi-walled nanotubes) will be presented. The physical hydrogen adsorption capacities (gravimetric and volumetric) of all these different types of carbon nanotubes will be presented and discussed. Post treatment processing of the carbon nanotubes and its effect on their hydrogen adsorption will be presented. The results of hydrogen adsorption on the high purity aligned MWNT will also be presented and used as a model for the role of nanotubes in hydrogen adsorption.
Dr. Michel J.-P. DEVEL
Laboratoire de Physique Moleculaire
16 route de GRAY
BESANCON CEDEX, 25030
FRANCE
(33) 3.81.66.64.76 (phone)
(33) 3.81.66.64.75 (fax)
------------------------------------------------------------
Title: Systematic study of carbon nanotubes static polarizabilities as a function of radius, length and helicity
Authors: M. Devel, Ch. Adessi
Affiliations: Laboratoire de Physique Moleculaire, 16 route de GRAY, 25030 Besancon CEDEX
Abstract:
Electron field emission by carbon nanotubes has very attractive properties for potential industrial applications such as flat panel displays. Its low turn-on field can be interpreted partly by the very high field enhancement at the tip of the nanotube. This enhancement can be linked to the nanotube polarizability. Previous studies on that subject used a tight-binding approximation for infinite length nanotubes (Benedict et al. Phys. Rev. B 1994, 52, 8541) or dipole-dipole interactions between the carbon atoms, for finite length nanotubes [(5,5) and (9,0)], with an isotropic carbon polarizability (Jensen et al., J. Phys. Chem B, 2000, 104, 10462) . We present here the results of a systematic study of carbon nanotubes static polarizabilities, using a dipole-dipole interaction model with anisotropic carbon polarizabilities, derived from graphite (P. Senet, Kirchberg 1993 ; M. Devel et al., Phys. Rev. B, 1996, 53, 13159). We show that the polarizabilities parallel and perpendicular to the tube axis are quadratic and linear functions of length, respectively, for fixed indices. Then, we study the influence of the radius on the previous proportionality coefficients, for a fixed helicity, and finally the influence of helicity. The resulting empirical laws can be used to predict the parallel and perpendicular polarizabilities of a wide class of single-wall carbon nanotubes.
Dr. Michel J.-P. DEVEL
Laboratoire de Physique Moleculaire
16 route de GRAY
BESANCON CEDEX, 25030
FRANCE
(33).3.81.66.64.76 (phone)
(33).3.81.66.64.75 (fax)
------------------------------------------------------------
Title: Field enhancement properties of carbon nanotubes
Authors: Ch. Adessi, M. Devel
Affiliations: Laboratoire de Physique Moleculaire, 16 route de GRAY, 25030 BESANCON CEDEX
Abstract:
Flat panel displays represent a very promising technological application of field emission from carbon nanotubes films, thanks to their low turn-on field. One mechanism suspected to lead to this property, is the polarization of the nanotube in the applied field leading to a high enhancement of the field. We have therefore studied the evolution of the field enhancement factor for various single-wall, double-wall and triple-wall nanotubes, by means of a self-consistent resolution of Poisson's equation in a dipolar approximation (Ch. Adessi et al., Phys. Rev. B, 2000, 62, R13314). Large differences between the $\beta$ factor of (n,0) and (n,n) nanotubes are observed. Actually, a saturation of the field enhancement with the length of the tube is observed for (n,n) nanotubes conversely to (n,0) nanotubes which can lead, for small diameter nanotubes, to very high value of the $\beta$ factor as observed experimentally. Moreover, we have verified, in the case of multi-wall nanotubes, that the inner shell holds up its field enhancement property. Finally, the effect of the nanotube density on the field enhancement is reported for a nanotubes film.
Mr. Orest Dubay
Institut für Materialphysik
Universität Wien
Sensengasse 8
Wien, A-1090
Austria
43 1 4277 51402 (phone)
(fax)
------------------------------------------------------------
Title: Accurate density functional calculations of phonons in carbon nanotubes
Authors: Orest dubay, Georg Kresse, Hans Kuzmany
Affiliations:
Abstract:
The phonon dispersion relations of armchair and zigzag single-wall carbon nanotubes are calculated using an all electron ab-initio density-functional method.[1] The behavior of the characteristic phonon branches, such as the radial breathing mode, twistons, the high-frequency optic modes and their dependence on the radius and the chirality are studied. The resulting spectra are in very good agreement with those obtained by the zone-folding method. We also present accurate force constants for isolated graphene sheets, which reproduce the experimental data with few percent accuracy. These force constants can be used for the study of the phonon dispersion relations of chiral tubes which are not directly tractable by first principle methods. [1] G. Kresse, and J. Joubert, Phys. Rev. B 59, 1758 (1999).
Mr. Fumiyuki Hoshi
Japan Fine Ceramics Center
1-1 Higashi, Tsukuba, Ibaraki 305-8565 JAPAN
, 305-8565
Japan
+81-298-61-9982 (phone)
+81-298-61-4796 (fax)
------------------------------------------------------------
Title: Isotope effects of CH_4 in synthesis of single-walled and multi-walled carbon nanotube by thermal chemical vapor deposition
Authors: Fumiyuki Hoshi^{1)}, Takefumi Ishikura^{1)}, Kei Kikuchi^{2)}, Akiko Goto^{1)}, Satoshi Ohshima^{3)}, Motoo Yumura^{3)}, Yoshinori Koga^{3)}, Shuzou Fujiwara^{3)}
Affiliations: 1:Frontier Carbon Technology Research Department, Japan Fine Ceramics Center 2:Frontier Technology Laboratory, Tokyo Gas Co., LTD. 3:National Institute of Materials and Chemical Research
Abstract:
We did the control composition of single wall carbon nanotube (SWCNT) and aligned multi wall carbon nanotube (MWCNT) on Si substrate from argon and methane as a carbon source by thermal chemical vapor deposition method.We used three kinds of CH_4 in the different isotope ratio.One is a natural abundance isotope ratio which composed of 98.9\% ^{12}CH_4 and 1.1\% ^{13}CH_4.The others are ^{12}C and ^{13}C enrichment of stable isotope CH_4 gas by cryogenic distillation of a natural abundance CH_4. The isotope enriching purity is 99.95\% for ^{12}C, and 99\% for ^{13}C. At first, we used CH_4 which is a natural abundance isotope ratio as a carbon source. We have fabricated SWCNT using a catalyst consisting of Fe or Co or Ni oxide with Mo oxide supported Al_2O_3 particles on Si substrate. SWCNT were grown at 900$^{\circ}$C. Its diameter is 0.5 - 1.2 nm. And we have fabricated MWCNT. The metal of Pd or Fe or Co or Ni was utilized by thermal evaporation method. MWCNT were grown at 1100 - 1200$^{\circ}$C.Its diameter is 150 - 200 nm. Second, I do similar experiments using isotope CH_4 (^{12}CH_4, ^{13}CH_4) as raw materials. We report results of spectrum shift of IR and Raman. [1] Jing Kong, Hyongsok T.soh, Alan M.Cassell, Calvin F.Quake & Hongjie Dai.,Nature, 395(1998), 878-881
Dr. Klaus Mauthner
Electrovac GesmbH
Aufeldgasse 37
Klosterneuburg, 3400
Austria
+43/2243/450 408 (phone)
+43/2243/450 698 (fax)
------------------------------------------------------------
Title: High Volume Production of Vapor Grown Carbon Nanofibers
Authors: Erich Leister, Ernst Hammel, Christian Nagl and Klaus Mauthner
Affiliations:
Abstract:
The serendipitous discovery of carbon nanotubes one decade ago has led to a new boost in carbon nanofiber technology. The structural perfection of this type of tubular graphitic carbon quickly revealed unexpected physical and chemical properties, which led to new visions and concepts in material science. As described in a great many deal of papers and patents tubular graphitic carbon might be introduced to a wide field of technical applications, like ultra light fiber reinforced composites, both with metals and plastics, in pastes as lubricant, electric or thermal conductor, in advanced coatings and as storage medium for hydrogen as well. So far so good, if there would not be the basic problem of production on a scale satisfying the demand for practical field tests at reasonable raw material costs. Though not yet fully understood in all detail, the catalytic activity of the iron group metals Fe, Co and Ni, respectively, being responsible for nanotube formation is well known and documented. Following this principle, we have developed a simple and cost effective CVD methodology yielding substantial amounts of nano fiber material in quantities between 50 and 200 grams per experiment in a pilot reactor unit. The wide range of yields is determined by the material quality finally obtained. As a rule of thumb it might be stated, that, the thinner the fibers and narrower the diameter distribution the lower the yield. As will be presented, the fiber diameters can be predetermined within a relatively small range, starting at 50 nm up to thick pyrocarbon coated fibers of several hundreds of nano meters. Structural features with respect to potential applications will be outlined.
Dr. Günther E Philipp
Max-Planck Institut für Festkörperforschung
Heisenbergstr. 1

Stuttgart, 70569
Germany
0711-6891574 (phone)
0711-6891572 (fax)
------------------------------------------------------------
Title: TEM and SFM investigation of single walled carbon nanotubes grown by CVD between microprinted catalyst islands
Authors: G. Philipp, G. Gu, X. Wu, M. Burghard, A. Bittner and S. Roth
Affiliations: Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany
Abstract:
Single-walled carbon nanotubes were grown between catalyst islands by chemical vapor deposition of methane and hydrogen. The deposition of the catalyst was performed using microcontact printing. This allows to produce a large number of samples with different patterns in much shorter time compared to electron beam lithography normally used to define catalyst positions. To charcterize the grown tubes, e.g. with respect to their exact diameter or the number of walls, it is crucial to examine them by transmission electron microscopy (TEM). Therefore the catalyst pattern was microprinted on ultrathin (20nm) silicon nitride substrates that are transparent for electrons and suitable for scanning force microscopy (SFM) as well. Thus it was possible to routinely study the obtained as-grown nanotube arrangement by TEM and SFM. In our investigation high quality individual single-walled carbon nanotubes with a broad diameter distribution were found, together with various types of crossings and junctions.

C - waiting list

Ms. Nathalie PIERARD
Facultés Universitaires Notre-Dame de la Paix (Laboratoire RMN)
61, rue de Bruxelles
Namur, 5000
Belgium
+3281724601 (phone)
+3281724600 (fax)
------------------------------------------------------------
Title: How to obtain short nanotubes with open tips
Authors: N. Piérard, A. Fonseca, Z. Konya, I.Willems, G. Bister and J. B.Nagy.
Affiliations: Facultés Universitaires Notre-Dame de la Paix, 61 rue de Bruxelles, 5000 Namur, Belgium.
Abstract:
The carbon nanotubes revealed to contribute to many fields of applications: field emission, electric and thermal conductivity, hydrogen storage, molecular sieve, etc. The last two applications require short nanotubes with open tips to overpass the diffusion limits. Our laboratory has developed a process to obtain short nanotubes with open tips in gram scale by using ball-milling processes. The cleavage is caused by the collision between one agate ball and the nanotubes powder contained in an agate mortar. Two types of products were studied: MWNTs produced on Co/NaY or Co-Fe/NaY and SWNTs produced on Co-Fe/MgO. The products were either crude (i.e. containing the catalyst and support) or purified (i.e. free of catalyst and support) or even oxidized to get rid of the amorphous carbon. The purified and oxided MWNTs size converges to 0.8 µm after 10 hours of ball-milling. For the others (crude or only purified), ball-milling treatment time must be increased. Only short nanotubes without amorphous carbon were detected. SWNTs required a shorter time of treatment to get shortened nanotubes because of their lower mechanical resistance: after a few hours, the SWNTs are destroyed leading finally to amorphous carbon.
Ms. Reeta Tarkiainen
Low Temperature Laboratory, Helsinki University of Technology
Low Temperature Laboratory
P.O. Box 2200
HUT, 02015
Finland
+358-9-4515795 (phone)
+358-9-4512969 (fax)
------------------------------------------------------------
Title: Shot noise and excess noise in multiwalled nanotubes
Authors: R. Tarkiainen, M. Ahlskog, L. Roschier, and P. Hakonen
Affiliations: Low Temperature Laboratory, Helsinki University of Technology
Abstract:
We have studied electric current noise in single, multiwalled carbon nanotubes using currents up to a few microamps, over frequency range 1 Hz - 12 kHz. We have mainly worked with arc-discharge grown tubes, in a geometry where the tube is on top of the gold electrodes. AFM manipulation was utilised in positioning the nanotube, when necessary. At highest frequencies we reach the shot noise limit. Our preliminary results, measured at 4.2 K, are close to simple shot noise given by \sqrt{2eI}. No reduction of noise due to correlations is seen, but some additional structure is visible. The low frequency noise was found to vary considerably from tube to tube. In general, our noise levels are lower than those reported for SWNTs by Collins et al., as might be expected due to the larger amount of charge carriers in MWNTs. In addition to 1/f^{\{alpha}} spectrum, in most samples there is also a two-level fluctuator type of contribution. The magnitude and lifetime of the fluctuators depend on the particular sample in question, and change with the bias voltage, which obscures the expected S_{I} \propto I^{2} dependence for resistance fluctuations.
Dr. Xinhe Tang
Electrovac GmbH
Aufeldgasse 37-39
Klosterneuburg, 3400
Austria
0043-2243-450405 (phone)
0043-2243-450698 (fax)
------------------------------------------------------------
Title: Characterisation of large area carbon nanofibre emitter
Authors: X. Tang*, E. Hammel, C. Nagl and K. Mauthner
Affiliations:
Abstract:
The advanced electronic properties have made carbon nanofibres/nanotubes very attractive for many potential applications, including as electron field emitters in flat panel displays and in flat CRT televisions. Although carbon nanotubes could be prepared at a relatively low temperature on various substrate materials, there still exist some critical problems growing carbon nanofibres on large area substrates by conventional CVD procedure, such as the adhesion between nanofibres and substrate, the homogeneous distribution of emitting sites, the reproducibility and stability of field emission and the scale up to bigger substrate size as well. Recently, we have successfully developed a new process to overcome the above mentioned difficulties. It has now been found that this novel process is suitable to fabricate large area carbon nanofibre cathodes at temperatures ranging from 800°C down to 400°C or even lower with a very high cost effectiveness. Using this technology, homogeneous carbon nanofibre growth has been achieved. The performance of these carbon nanofibre emitters is presented in this paper. Field emission experiments with luminescent anodes have shown homogeneous distribution of emitting sites. A current density, 0.8mA/cm2 at field 1.8V/µm was measured over an emitting area of 2 cm x 2 cm. Moreover, the scale up to produce large emitting areas up to 8 inch in diameter is feasible, depending on the dimensions of the reaction chamber.
Dr. Marc in het Panhuis
Materials Ireland Polymer Research Centre
Department of Physics
Trinity College
Dublin, 1
Ireland
+353 1608 3595 (phone)
+353 1671 1759 (fax)
------------------------------------------------------------
Title: Quantifying conduction behavior in a nanoscale field effect transistor
Authors: Marc in het Panhuis(1), R.W. Munn(2), P.L.A. Popelier(2), J.N. Coleman(1), W.J. Blau(1)
Affiliations: (1) Materials Ireland Polymer Research Centre, Department of Physics, Trinity College Dublin, Dublin 2, Ireland. (2) Department of Chemistry, UMIST, Manchester M60 1QD, UK
Abstract:
In 1947 the fastest electronic computer on earth, the ENIAC weighed 27 tons, consumed 170 kW of power and filled about 460 m3 space. Computing hardware has made a tremendous development since then. Current state of the art personal computers weigh little over one kg and run on small batteries. Computer chips are still shrinking according to Moore’s Law; every 12 – 24 months the number of transistor on a silicon chip doubles. However, Moore’s Law will be reaching its physical limits within the next two decades. Therefore, in order for computational power to keep increasing, it is necessary to design a transistor that can take us past Moore’s Law. A novel nanoscale transistor device that can fulfill this requirement is presented. Single walled carbon nanotubes (SWNT), with metallic properties, act as interconnects for the active element, a single molecule or bio-molecule. The active element is used to switch the transistor between ON and OFF states. Ab inito computer simulation is used to quantify the conduction behaviour.
Mr. KwangSeok Jeong
Samsung Advanced Institute of Technology
P.O. Box 111, Suwon 440-600, Korea
Suwon, Kyung Ki Do
Rep. of Korea
82-31-280-9398 (phone)
82-31-280-9349 (fax)
------------------------------------------------------------
Title: Thermal effects on the electrical properties of multi-walled carbon nanotubes
Authors: K.S. Jeong^{1} , J.U. Chu^{1} , E.J. Bae^{1} , G.S. Park^{3}, W.B. Choi^{1,2};
Affiliations: ^{2} Microelectronics Lab ^{1} The National Program for Tera-Level Nanodevices, ^{3} Analytical Engineering Lab
Abstract:
Thermal annealing effect on the electrical properties of multi wall carbon nanotube is investigated. Two types of multi wall carbon nanotube, which are grown by thermal CVD and arc-discharged technique, are prepared. Highly ordered carbon nanotubes are fabricated by using anodic porous alumina nano-template. Anodic porous alumina templates are obtained by the electrochemical anodizing method. Multiwall carbon nanotube powder was obtained by using conventional arc discharge technique. Annealing effects on the electrical properties of multiwall carbon nanotube are investigated by measuring I-V characteristic, TEM, Raman, and EELS. It was observed that the electronic transport of carbon nanotube is changed by anealing time and temperature. The change of electrical properties together with atomic structure will be discussed.
Ms. SeungJong Lee
Yonsei Univ.
hinFilm Materials Lab. Department of Metallurigical Engineering
134 ShinchonDong SeoDaeMunGu
Seoul, 120-749
South Korea
82-2-2123-2838 (phone)
82-2-312-5275 (fax)
------------------------------------------------------------
Title: Mass production of carbon nanotubes by the plasma rotating arc discharge
Authors: Seung Jong Lee, Hong Koo Baik
Affiliations: Yonsei University
Abstract:
The large scale synthesis of carbon nanotubes is achieved by the plasma rotating electrode process(PREP). The graphite anode is rotated at the high velocity for the synthesis of carbon nanotubes. In conventional arc discharge, nanotubes are produced on the cathode surface and the electrode spacing is not constant, so the current flow is not uniform and the electric fields are not homogeneous. Rotating electrode distributes the microdischarge uniformly and it makes the plane-to-plane microdischarge in comparison with the point-to-point discharge in conventional arc discharge. In PREP, the discharge volume, the gas temperature of the plasma and the quantity of the carbon vapor increase. So nanotube is formed by the condensation of carbon vapor when the centrifugal force generated by the rotation of electrode will transfer the high density carbon vapor out of the plasma region with the high velocity. Changing the synthetic pre-conditions identifies the elements of producing carbon nanotubes: the density of carbon and the growth temperature through the variation of the rotating speed of the electrode and the distance between the plasma and the collector. The synthesis of carbon nanotubes by the PREP can run in the continuous fashion and can be scaled up for industrial production levels.
Mr. Gyuseok Choi
Chungnam National University
220 Gungdong Yusong Chungnam National University
Department of Materials engineering
Taejon, Chungnam
South KOREA
+82-42-821-7648 (phone)
+82-42-823-4224 (fax)
------------------------------------------------------------
Title: Patterned growth and field emission properties of aligned carbon nanotube based Diode and Triode type field emission array
Authors: Gyseok Choi, Yusuk Cho, Sangyoung Hong, Dojin Kim, Youngho Song*,Jinho Lee, Kyungik Cho*
Affiliations: Department of materials engineering, Chungnam National University *Electrinic Telecomunication Reaserch Institues
Abstract:
We have grown vertically aligned carbon nanotube based diode and triode type field emission array on Si substrate by thermal chemical vapor deposition at 800~900°C. As grown carbon nanotube has high density and uniform distribution and ~50nm diameter with multi-wall structure and ~30mm length. The field emission measurement has been carried out on the carbon nanotube-cathode diode and triode device at room temperature and in a vacuum chamber. The size and distance of pattern is 5mm2, 10mm2, 20mm2 respectively and the geometric factor of emission array effects on the emission property, such as maximum emission current and turn on voltage of CNT-emission array. The electron field emission of the as grown patterned carbon nanotube can be turned on with a field as low as 1.31V/mm and attain a current density as large as 1mA/cm2 at a field of 2.5 V/mm for 5mm2 size and distance. By contrast, the electron field emission of the 20mm2 size can be turned on at 3.03V/mm, attaining a emission current density of 200mA/cm2 at a field of 4.41 V/mm The size and distance of CNT emission array by patterning are important factor for the CNT based field emission array.
Mr. Young Joon Yoon
Dept. of Metallurgical Eng. Yonsei University
134 Shinchon-dong, Seodaemun-ku
Seoul, 120-749
Korea
82-2-2123-2838 (phone)
82-2-2123-9846 (fax)
------------------------------------------------------------
Title: Growth control of carbon nanotubes in a chemical vapor deposition process
Authors: Young Joon Yoon, Hong Koo Baik
Affiliations: Department of Metallurgical Engineering, Yonsei University
Abstract:
There have been many reports for the synthesis of carbon nanotubes (CNTs) by a chemical vapor deposition (CVD). However, the CNTs grown by a CVD process show mostly multi-walled structure with a few tens of nanometer diameters, because it is difficult to prepare catalyst particles with a few nm sizes. Therefore, there have been few reports for the synthesis of single-walled carbon nanotubes (SWNTs) by using metal catalysts in a CVD process except gas phase reaction method. In this presentation, we developed a useful method for preparing catalysts on a flat substrate with a few nm scales by an agglomeration process. Thin film of transition metals, Co, Ni, and Fe, was deposited on a thermally oxidized silicon wafer in angstrom scale by D. C. magnetron sputtering system attached with an accurate thickness monitoring system. It was transformed easily into a few nm size particles by heating in thermal CVD reactor. Then, SWNTs or MWNTs less than 10nm size could be synthesized by controlling the flux and partial pressure of hydrocarbon gas, respectively. This method is useful due to the direct formation of SWNTs on the substrate.
Dr. Mirko Croci
Ecole Polytechnique Fédérale de Lausanne
IPE-DP
EPFL
Lausanne, VD 1015
Switzerland
+41 21 693 4404 (phone)
+41 21 693 3604 (fax)
------------------------------------------------------------
Title: FIELD EMISSION IN CYLINDRICAL GEOMETRY WITH CARBON NANOTUBE CATHODES
Authors: Mirko Croci, Olivier Noury, Thomas Stockli, Andre Chatelain and Jean-Marc Bonard
Affiliations: Departement de Physique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne
Abstract:
There have been in the past some unsuccessful attemps to realize lighting elements with field emitters to offer an alternative to incandescent or fluorescent lamps. Such an element would consist of a cylindrical glass tube with a phosphor layer on the inner surface that is bombarded with energetic electrons emitted by the cathode. To ensure a uniform light emission, the cathode itself must be cylindrical, and the problem of depositing field emitters on a non-planar surface has up-to-now prevented the realization of such devices. We report here on the successful realization of a field emission diode in a cylindrical geometry, with multiwall carbon nanotubes deposited on the metallic cathode as the electron sources. The field emitters show excellent performances and can be used to realize luminescent mercury-free tubes. We show also how the cylindrical geometry allows one to gain easily additional informations on the different parameters involved in the field emission (e.g., space-charge related problems, influence of residual gas pressure and of adsorbates).
Mr. Olivier Smiljanic
INRS Énergie et Matériaux
1650 bd. Lionel Boulet
Varennes, Québec J3X 1S2
Canada
(450) 929-8237 (phone)
(450) 929-8102 (fax)
------------------------------------------------------------
Title: Growth of carbon nanotubes on Ohmically-heated carbon paper
Authors: Olivier Smiljanic^{1}, Tarik Dellero^{1}, Alessandra Serventi^{1}, Jean-Pol Dodelet^{1}, Guy Lebrun^{1}, Barry L. Stansfield^{1}, Michel Trudeau^{2}, Sylvain Désilets^{3}
Affiliations: ^{1} INRS-Énergie et Matériaux, Varennes, Québec, ^{2} IREQ, Varennes, Québec, ^{3} CRDV, Val Belair, Québec
Abstract:
Multi-wall carbon nanotubes (MWNTs) have been grown from ethylene on fibers of carbon paper by Ohmically heating the catalytic sites deposited on the carbon fibers. Both chemical (via the reduction of metal nitrates) and physical (via nanoparticles produced in a hollow cathode discharge) approaches have been used to deposit the catalyst. Iron, nickel, and cobalt, as well as combinations of these metals have been used. The MWNT are mainly (but not exclusively) tip-grown, and have diameters ranging from 7 to 30 nm, depending on the growth scenario. We will report on recent experiments designed to produce smaller diameter nanotubes.
Mr. Mark Hughes
Cambridge University
Corpus Christi College
Cambridge, Cambs CB2 1RH
UK
+44 1223 334335 (phone)
+44 1223 334567 (fax)
------------------------------------------------------------
Title: Structural Characterisation of Carbon Nanotube/Conducting Polymer Composites
Authors: Mark Hughes, George Z. Chen, Milo S.P. Shaffer, Alan H. Windle, Derek J. Fray
Affiliations: Department of Materials Science and Metallurgy, University of Cambridge
Abstract:
Composites of carbon nanotubes and conducting polymers are attractive for their ability to merge the exceptional mechanical, physical and electrical properties of these two unique materials. The structure of such a combination is crucial in determining its performance and is largely dependent on the fabrication conditions employed. Composites of multi-walled nanotubes and polypyrrole were grown via an electrochemical route. Scanning electron microscopy was used to examine the effect of several production parameters on the structures produced. It was found that the amount of polypyrrole coated onto each carbon nanotube was dependent on a range of factors, particularly the type and concentration of supporting electrolyte employed. By manipulating these conditions, it was possible to produce a variety of structures ranging from an open porous network of polypyrrole-coated nanotubes to a completely solid carbon nanotube/polypyrrole composite.
Mr. Jaeuk Chu
Samsung Advanced Institute of Technology
Nongseori 14
Yong In, Kyungki do 440-600
Korea
82-31-280-9351 (phone)
82-31-280-9349 (fax)
------------------------------------------------------------
Title: Electrical and Magnetotransport Properties of Vertically Grown Carbon nanotube
Authors: J.U. Chu^{2} , K.S. Jeong^{2} , E.J. Bae^{2} , J.H Sok^{1}, W.B. Choi^{1},J.O. Lee^{3} , J.J Kim^{3};
Affiliations: ^{1}Microelectronics Lab Samsung Advanced Institute of Technology Suwon Korea, ^{2}The National Program for Tera-Level Nanodevices Samsung Advanced Institute of Technology Suwon Korea , ^{3}Department of Physics Chonbuk National University Chonju 561-756 Korea
Abstract:
Highly ordered alumina array which hole size is decreased down to 20nm was fabricated by anodization technique. Carbon nanotube was grown vertically with thermal CVD at 600-800? and analyzed by SEM and TEM. Ohmic contact was formed between carbon nanotube and metal electrode by using rapid thermal annealing method. The electrical and magnetotransport properties of vertically grown carbon nanotube as a function of temperature were studied. It was found that the measured differential conductance and magnetoresistance critically dependent on the magnetic field. The temperature dependence of the resistance at a function of magnetic field was observed. The novel device structure of carbon nanotube with nano size patterned electrode is proposed.
Mr. Kwang Seok Jeong
Samsung Advanced Institute of Technology
P.O. Box 111, Suwon, Korea
Suwon, KyoungKi-Do 440-600
South Korea
82-31-280-9398 (phone)
82-31-280-9349 (fax)
------------------------------------------------------------
Title: Thermal effects on the electrical properties of multi-walled carbon nanotubes
Authors: K.S Jeong^{2} , J.U.Chu^{2} , G.S.Park^{3} , W.B.Choi^{1,2};
Affiliations: ^{1}The Microelectronics Lab. Samsung Advanced Institute of Technology Suwon Korea , ^{2} The National Program for Tera-Level Nanodevices Samsung Advanced Institute of Technology Suwon Korea, ^{3}Analytical Engineering Lab. Samsung Advanced Institute of Technology Suwon Korea
Abstract:
Dr. Wolfram Knapp
Otto-von-Guericke-Universitaet Magdeburg, Abt. Vakuumphysik
Universitaetsplatz 2
Magdeburg, Sachsen-Anhalt 39106
Germany
+49-391 6712505 (phone)
+49-391 6718109 (fax)
------------------------------------------------------------
Title: Field Emission Characteristics of Carbon Nanotubes Paper
Authors: W. Knapp, D. Schleussner
Affiliations: Otto-von-Guericke-Universitaet Magdeburg, Abt. Vakuumphysik und -technik
Abstract:
Carbon nanotubes have recently emerged as one of the most promising electron field emitters. Large array field emitters are becoming increasingly important in field emitter applications. Carbon nanotubes can be used as large array field emitter in two different types of set-ups, namely free-standing well-aligned carbon nanotubes and chaotic-lying non-aligned carbon nanotubes. A typical representative of the second kind is carbon nanotubes paper. We investigated carbon nanotubes paper (pieces of some cm²; thickness of about 70 µm) of chemically purified single-walled nanotubes (purity: 50-70 vol %; diameters: 5-10 nm). With this structure good field emission properties are obtained. The threshold electric field for field emission is in the range of 1 V/µm. The obtained emission current densities are about 1 mA/cm². The long-term electron emission stability is proved. Because the surface structure is repeated in the paper bulk, we assume that carbon nanotubes paper is a highly resistant large array field emitter with a long lifetime. To proof the assumption reproducible stress tests with ion bombardments and controlled discharges for chemical and physical erosion are carried out. First results are presented.
Dr. Arkady V. Krasheninnikov
Accelerator Laboratory, University of Helsinki
Accelerator Laboratory, P.O. Box 43,
FIN-00014 University of Helsinki, Finland
Helsinki,
Finland
+358-9-19150003 (phone)
+358-9-19150042 (fax)
------------------------------------------------------------
Title: Formation and evolution of ion irradiation-induced atomic-scale defects on walls of carbon nanotubes
Authors: A. V. Krasheninnikov, K. Nordlund, M. Sirvi\o, and J. Keinonen
Affiliations: Accelerator Laboratory, P.O. Box 43, FIN-00014 University of Helsinki, Finland
Abstract:
Recent experiments on irradiated carbon nanotubes evidence that ion bombardment gives rise to their amorphization and dramatic dimensional changes. Using molecular dynamics, we study the structure and formation probabilities of atomic-scale defects produced by low-dose irradiation of nanotubes with Ar ions. For this, we simulate impact events over a wide energy range of incident ions. We show that the maximum damage production occurs for a bombarding ion energy of roughly 600 eV and that the most common defects produced at all energies are vacancies, which at low temperatures are metastable but long-lived defects. We also study how they transform to other defects and estimate the stability of these defects. Employing the tight-binding Green's function technique, we further calculate STM images of irradiated nanotubes. We demonstrate that irradiation-induced defects may be detected by STM and that isolated vacancies may look like bright spots in atomically-resolved STM images of irradiated nanotubes. We calculate the STM images of other irradiation-induced defects as well. We also discuss employing focused electron and ion irradiation for producing nanotube-based quantum dots, which may potentially be used as electronic device components.
Dr. Yajun Tian
State Key Lab of C1 Chemistry and Technology
Yingze West Sreet 79#
Taiyuan University of Technology
Taiyuan, Shanxi 030024
China
86-351-6017020 (phone)
(fax)
------------------------------------------------------------
Title: Nanotube formed in arc plasma jet from coal
Authors: Tian Yajun, Xie Kechang
Affiliations: State Key Lab of C1Chemistry and Technology
Abstract:
In general, nanotube is manufactured by the means of arc discharging between the parent materials(such as graphiter) and cathod, so that the high temperature of the arc column could be used effectively. In our lab, parent coal is injected into the arc plasma jet with the average temperature of 3600K, nanotube cluster was found in the hard carbon deposited on reactor wall. These nanotube with the diameter of 20nm is characterized by HRTEM.
Dr. Shaoming Huang
CSIRO Molecular Science Division
Bag 10, Claton South
, Victoria 3169
AUSTRALIA
61-3-95452524 (phone)
61-3-95452589 (fax)
------------------------------------------------------------
Title: Nano-patterning Aligned Carbon Nanotubes/nanofibres
Authors: Shaoming Huang, Liming Dai and Albert W. H. Mau
Affiliations: CSIRO Molecular Science, Australia
Abstract:
Nano-patterning aligned carbon nanotubes (CNTs)/nanofibres(CNFs) possesses fundamental scientific and practical application importance. We have focussed our effort on the design and fabrication of aligned CNTs/CNFs patterns in large area by either pre-patterning catalysts or polymers for substrate-site selective growth of CNTs/NTFs based on chemical vapor deposition( pyrolysis of molecules containing both the metal catalyst and carbon source such as iron(III) phthalocyanine and hydrocarbon such as acetylene). A few methods including physical mask, photolithography and soft-lithography have been applied for pre-patterning both catalysts and polymers. The resolution of the formed aligned CNTs/CNFs patterns can be down to micrometer and different structural features of the aligned CNTs/CNFs patterns such as multi-dimensional patterns can be achieved by controlling experimental conditions. Basically, for aligned CNFs patterns the glass substrate is used and CVD temperature is lower than 650 °C. The applications of the designed and fabricated aligned CNTs/CNFs patterns in flat panel display, energy storage, security device and nano-electronics are being under investigation.
Dr. Vladislav A. Ryzhkov
Rosseter Holdings Ltd
4 Nikiforou Lytra
P.O.Box 56860
Limassol, 3310
Cyprus
+357-5-581336 (phone)
+357-5-591888 (fax)
------------------------------------------------------------
Title: ON PRODUCING CARBON NANOTUBES BY A CONTACT AUTO-REGULATED ARC DISCHARGE IN LIQUID HYDROCARBONS
Authors: Vladislav A. Ryzhkov
Affiliations: Rosseter Holdings Ltd, P.O.Box 56860, 3310 Limassol, Cyprus
Abstract:
The paper suggests a new technology for producing carbon nanotubes under a contact auto-regulated arc discharge in a liquid hydrocarbon medium containing aromatics and/or cylcloarenes. A special geometry of our electrode system allows producing nanotube deposits with a yield of 1-5 g/min per a pair of the electrodes. In TEM pictures the nanotube deposits appear as mixtures of MWNT, SWNT and bucky-onions. Under our best regimes TEM shows a very narrow diameter distribution of MWNTs with a maximum at 6 nm and an average number of layers about 5-6, whereas SWNTs appear with diameters in the range 4-10 nm. XRD determines 40-60% of MWNTs and 3-10% of bucky-onions in the deposits. Raman spectrometry shows an absence of SWNTs with diameters lower than 1.5 nm. Electron emission measurements confirm that our nanotube deposits are suitable for such applications as flat panel monitors, cold cathodes, etc. Using “soft” oxidation regimes allows advancing the nanotubes for hydrogen storage applications. Some new phenomena, including cylindrical colloidal aggregations as well as flat nanotubes' aggregations, observed by TEM, are reported in the paper.
Dr. Cornelis Lensink
Industrial Research Limited
PO BOX 31 310
Lower Hutt, . .
New Zealand
+ 64 4 569 0000 (phone)
+64 4 590 0142 (fax)
------------------------------------------------------------
Title: Aerosil supported SWNT synthesis
Authors: C.Lensink, K. Edgar
Affiliations: Industrial Research Limited
Abstract:
Alumina modified aerosil of various grades was used as a support for Iron/Molybdenum catalyst particles. Decomposition of methane over thiese catalysts at elevated temperatures yields predominantly single wall nanotubes (SWNT). This poster reports on our study of the effect of alumina loading and Fe/Mo loading on the available surface area and its correlation with carbon yield as determined by TGA. We will also describe a method of isolation the SWNT's from the inorganic support.
Dr. Vladimir Lvovich Kuznetsov
Boreskov Institute of Catalysis
Lavrentieva 5
Novosibirsk, 630090
Russia
007 (3832) 343765 (phone)
007 (3832) 343056 (fax)
------------------------------------------------------------
Title: Thermodynamic analysis of carbon nucleation on the metal surface and it's implication for the growth of carbon nanotubes.
Authors: V.L.Kuznetsov*, A.N.Usoltseva*, A.L.Chuvilin*, E.D.Obraztsova**, and J.M.Bonard***
Affiliations: (*) Boreskov Institute of Catalysis, Russia, (**) Natural Science Center of Russian Academy of Sciences, Russia, (***) Institut de Physique Experimentale, EPFL, Switzerland
Abstract:
The consideration of mechanisms of catalytic formation of different carbon deposits (filamentous carbon, multi- and single-wall carbon nanotubes (SWNTs)) led us to conclusion that majority of these mechanisms include some common steps. We suggest that the most important of them is the step of nucleation of carbon deposit on the metal surface. We have proposed that carbon nucleus has the form of flat saucer with its edges bonded to the metal surface. The thermodynamic analysis of carbon nucleation process, which based on the consideration of variation in Gibbs free energy in the case of carbon nucleus formation, was performed. This analysis results in the functional dependence between the critical radius of the carbon nucleus and reaction parameters such as reaction temperature, carbon content in a metal-carbon particle and parameters, which characterize the nature of metal catalyst. The main conclusions are: a) an increase of the temperature leads to the formation of smaller nuclei and finally to the formation of SWNTs; b) the use of metals, with higher metal-carbon energy bond, yields nanotubes with smaller diameters; c) SWNT growth is likely to proceed on liquid metal particles; d) elements that decrease the melting point of the catalyst-carbon mixture promote also the formation of SWNTs.
Mr. Martin Cadek
University of Dublin, Trinity College
Trinity College Dublin
Department of Physics
Dublin, 2
Ireland
+353-87-653-1764 (phone)
+353/1-571 1759 (fax)
------------------------------------------------------------
Title: Characterisation of Polymer Nanotube Composite
Authors: M. Cadek
Affiliations: M. in het Panhuis, J.N. Coleman, W. J. Blau
Abstract:
Applications for carbon nanotube containing material range from use in displays, hydrogen storage or as use for reinforcement material for use in bullet proof jackets or space coats. Nanotubes are not soluble in common solvent such as toluene and water. Therefore, the nanotubes are placed in a polymer host in solution. The resulting solution can then be processed into a film or bulk material. Our composite material are made using multi wall carbon nanotubes (MWNT) and poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) (PmPV), which is soluble in toluene. In addition to this, composites where made using poly(vinyl alcohol) (PVA) polymer, which is soluble in water and poly(9-vinylcarbozole) (PVK) which is soluble in dichlormethane (DCM). Optical, electrical and mechanical measurements of PmPV-nanotube composites are compared to PVA-nanotube composite materials.
Dr. Marc in het Panhuis
Materials Ireland Polymer Research Centre
Physics Department
Trinity College
Dublin, 2
Ireland
+353 1608 3595 (phone)
+353 1671 1759 (fax)
------------------------------------------------------------
Title: Solubility of Polymer-Nanotube Composites
Authors: Marc in het Panhuis(1), A. Miati(2), J.N. Coleman(1), A.B. Dalton(1), B. McCarthy(1), W.J. Blau(1)
Affiliations: (1) Materials Ireland Polymer Research Centre, Department of Physics, Trinity College Dublin, Dublin 2, Ireland. (2) Molecular Simulations Inc, 9685 Scranton Road, San Diego, California 92121-3752, USA.
Abstract:
Carbon nanotubes (CT) can be employed in a wide variety of applications including space suit reinforcements, radar absorbance material for stealth applications or as field emitters in display technology. This is due to their excellent structural, mechanical and electronic properties. One of the main impediments is processing nanotubes. Based on their hydrophobic nature it was thought that CT would dissolve in a hydrophobic solvent such as toluene. However, nanotubes fall out of toluene solution. It has been demonstrated that nanotubes can be rendered soluble using a polymer matrix. Computer simulation and experimental evidence are combined to identify the binding energy necessary to disperse nanotube bundles using poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) (PmPV) polymer. Furthermore, the wrapping of PmPV onto single walled nanotubes in composites is investigated.
Dr. Igor Bazhin
Don Technical University
Gagarin Sq. 1
Rostov-on-Don, Rostov Region 344010
Russia
(8632)713305 (phone)
(fax)
------------------------------------------------------------
Title: Formation of polymerized MxC60 (M = Ti, Cr and Nb)
Authors: I.V.Bazhin and A.P.Popov
Affiliations: Dept. of Physics, Don State Technical University, Rostov-on-Don, Gagarin Sq. 1, 344010, Russia
Abstract:
Fullerene-like compounds have a variety of unique physical properties explaining the increased interest to them. It is possible to assume that transition-metal fullerides will have a number of interesting features by analogy with their carbides. The purpose of the paper is investigation of interaction fullerene with Ti, Cr and Nb [1-2]. The electronic and chemical properties of metal-fullerene products were carried out using ab initio GAMESS calculations with STO-3G and 3-21G basis sets. At first the process of formation of the exohedral fullerene complexes was investigated. Is shown that to atom or atomic dimer of transition-metal energetic favourably incorporates to a molecule on the part of a six-coal side. The computation experiment has shown that metal-fullerene polymerization is carried out through atoms of metal which count a role of peculiar bridges. The values x for the most stable complexes MxC60 (M = Ti, Cr and Nb) have been found. The calculated DOS is in the good agreement with experimental XPS spectra for TixC60 [3]. 1. W.Zhao, Y.Li, L.Chen, Z.Lu, Y.Huang, and Z.Zhao, Solid State Commun. 92, 313 (1994). 2. J.Fye, M.Jarrold, Int. J. Mass Spectrometry, 185-1987, 507 (1999). 3. L.Qian, L.Norin, J.Guo, C.Sathe, A.Agui, U.Jansson, J.Nordgren, Phys. Rev. B59, 12667 (1999).
Dr. Boris P. Tarasov
Institute of Problems of Chemical Physics, RAS
Institutskii Str., 18
Chernogolovka, Moscow Region 142432
Russia
+7-096-522-7707 (phone)
+7-096-524-4401 (fax)
------------------------------------------------------------
Title: Carbon nanomaterials as hydrogen sorbents
Authors: B.P.Tarasov$^1$, Yu.M.Shul'ga$^1$, V.N.Fokin$^1$, V.E.Muradyan$^1$, E.P.Krinichnaya$^1$, O.N.Golodkov$^1$, O.N.Efimov$^1$, S.Yu.Zaginaichenko$^2$, D.V.Schur$^2$, P.J.Mahlen$^2$, B.C.Hauback$^3$, V.Yartys$^3$
Affiliations: $^1$ Institute of Problems of Chemical Physics of RAS, Chernogolovka, Russia; $^2$ Institute of Problems of Materials Science of NASU, Kiev, Ukraine; $^3$ Institute for Energy Technology, Kjeller, Norway
Abstract:
We report here the results of research on synthesis, purification, and certification of single-walled carbon nanotubes (SWNT) and graphene nanofibers (GNF). The data on their hydrogen-sorbing properties are discussed. SWNT were obtained by electric arc evaporation of graphite involving various catalysts of the Co-Ni, Ni-Y and Ni-Co-Fe series and were isolated by thermooxidation and treatment with acids. GNF were obtained by catalytic pyrolysis of C$^2$H$^2$ and C$^2$H$^4$ on powders of Ni, Co and their intermetallic compounds at 850-1000 K and under partial pressure of 100-400 Torr. Carbon nanostructures synthesized were analyzed by TEM, TGA, IR- and Raman spectroscopy, X-ray diffraction and chemical analyses and by specific surface and magnetic characteristics measurements. The investigations of hydrogen-sorbing properties of carbon materials were carried out in the temperature of 77-300 K and pressure of 10${-4}^$-10 MPa. It was found that under these conditions the material containing ~70 mass. % of SWNT reversibly absorbs ~3.5 mass. % of hydrogen, and the pyrolysis product containing ~50 mass. % of GNF absorbs ~2.5 mass. % of hydrogen. The reasons of divergence of the data obtained by us and other authors on the amount of hydrogen adsorbed by carbon nanomaterials, possible mechanisms of high hydrogen-sorbing capacity are discussed.
Dr. Alexander B. Kukushkin
RRC "Kurchatov Institute"
Kurchatov Sqr., 1
Moscow, 123182
Russia
7(095)1967334 (phone)
7(095)9430073 (fax)
------------------------------------------------------------
Title: May nanotubular structures assemble self-similar tubules up to centimeter size? Review of observations
Authors: A.B. Kukushkin, V.A. Rantsev-Kartinov
Affiliations: RRC "Kurchatov Institute"
Abstract:
A review is given of verifications of the hypothesis [1(a,b)] which suggested the long-lived filaments observed in various fusion plasmas (tokamaks, Z-pinches, plasma focus) to possess a microsolid skeleton which might be assembled during electric breakdown, well before plasma’s birth, from wildly produced carbon nanotubes (or similar nanostructures of other chemical elements). This includes, in particular, evidences for: (1) self-similar tubular structures in the range from several nanometers to several micrometers in diameter, found [2] in electronic micrographs of various types of dust deposit (submicron and micron particles, and films, mostly carbon ones) in tokamak T-10 (see another poster); (2) skeletons (tubules and «cartwheels» of centimeter/millimeter size) at electric breakdown stage of discharges in a gas (tokamak, plasma focus) and vacuum spark; (3) correlations of a «wild cable» model [1(c)] for self-protection of skeletons from ambient high-temperature plasmas with recent observations of anomalously low dissipation properties of «wild» cathode deposits with MWNTs. REFERENCES [1] Kukushkin A.B., Rantsev-Kartinov V.A., (a) Fusion Energy 1998 (IAEA, Vienna, 1999, IAEA-CSP-1/P, Vol. 3) p. 1131; (b) Proc. 26-th EPS PPCF (Maastricht, Netherlands, 1999) p. 873 (http://epsppd.epfl.ch/cross/p2087.htm); (c) Proc. 27-th EPS PPCF, Budapest, Hungary, 2000 (http://sgi30.rmki.kfki.hu/EPS2000/P2_028.pdf); [2] Kolbasov B.N., et. al., Phys. Lett., A269 (2000) 363.
Dr. Valentin A. Rantsev-Kartinov
RRC "Kurchatov Institute"
Kurchatov Sqr., 1
Moscow, 123182
Russia
7(095)1967334 (phone)
7(095)9430073 (fax)
------------------------------------------------------------
Title: Nano- and micron-size tubular structures in various dust deposits in tokamak T-10
Authors: B.N. Kolbasov, A.B. Kukushkin, V.A. Rantsev-Kartinov, P.V. Romanov
Affiliations: RRC "Kurchatov Institute"
Abstract:
For verifying the hypothesis [1(a,b)] for the presence, in the observed long-living filaments, of a microsolid skeleton assembled during electric breakdown from wildly formed (carbon) nanotubes, an analysis of electronic transmission and scanning micrographs of various types of dust deposit in tokamak T-10 found the self-similar tubular structures in the range from several nanometers to several micrometers in diameter [2], and the ability of nanometer tubular structures to build up the skeletons of various topology and spatial dimensionality (fibers, spheres, balls, dendritic structures). The trend of assembling larger tubules from smaller ones may go to much larger length scales (centimeters and larger) as it follows from the similarity of structures of easily distinguishable topology (tubules and especially cartwheels often located in the edge cross-section of a tubule) in the dust deposits and in the visible light images [1(c)] of plasma in tokamaks TM-2, T-4, T-6 and T-10. REFERENCES [1] Kukushkin A.B., Rantsev-Kartinov V.A., (a) Proc. 17th IAEA Fusion Energy Conf., Yokohama, Japan, 1998, v. 3, p. 1131; (b) Proc. 26-th EPS PPCF Conf., Maastricht, Netherlands, 1999, p. 873; (c) Proc. 27-th EPS PPCF Conf., Budapest, Hungary, 2000, P2_029. [2] Kolbasov B.N., et. al., Phys. Lett., A 269 (2000) 363.
Prof. Yurii M. Volfkovich
A.N. Frumkin Institute of Electrochemistry
Leninskii Prospect 31
Moscow, 117071
Russia
+7-095-9554019 (phone)
+7-095-9520846 (fax)
------------------------------------------------------------
Title: Electrochemical generation and oxidation of hydrogen in carbon nanomaterials of attested porous structure
Authors: $^a$Yu.M.Volfkovich ,$^a$ A.Yu. Rychagov ,$^a$V.E. Sosenkin, $^a$ N.F. Nikolskaya,$^b$ O.N. Efimov, $^b$ B.P. Tarasov ,$^b$ E.P.Krinichnaya,$^c$ R.O. Loutfy,A.P., $^{b,c} $ Moravsky A.P.
Affiliations: $^a$A.N. Frumkin Institute of Electrochemistry,31 Leninskii Prospect, 117071 Moscow, Russia;$^b$ N.N. Semenov Institute of Problems of Chemical Physics, Chernogolovka, 142432 Moscov region, Russia, $^c$ MER Corporation, Tucson, AZ, U.S.
Abstract:
The porous structure of carbon nanomaterials (CNM) was investigated by the Method of Standard Porosimetry (MSP) [1] and Raman Spectroscopy (RS). The single wall carbon nanotubes (SWNTs) were prepared by the arc-discharge technique using a Co/Ni catalyst. The tubes have diameters from 1.2 to 1.8 nm. The SWNTs have been purified and to ca. 70 wt. % by air-oxidation technique which ensures opening of tubes. The specific volume of the internal channel is equal to 0,29 cm$^3$/g. The specific adsorption of hydrogen is 3,5 wt. % at 3 MPa. It implies the extraordinary strong attraction between hydrogen molecule and internal tube surface. The SWNT electrodes were used for a detailed study of their electrochemical behavior in 1N H2SO4 and a double layer supercapacitor was built and explored. A reversible peaks were found at E ~ - 0.2 V RHE on cyclic chrono-voltammetry curves and the appropriate capacity is 60 C/g. The peaks pertains to electrochemical generation-electrooxidation of hydrogen and its adsorption-desorption inside SWNTs. References 1. Yu. M.Volfkovich, V.S.Bagotzky, J. Power Sources, 48 (1994) 327, 339.
Dr. Zoia Yaroslavovna Kosakovskaya
Institute of Radio Engineering and Electronics of RAS
Mokhovaya , 11
Moscow, 101999
Russia
7-095-2033689 (phone)
7-095-2038414 (fax)
------------------------------------------------------------
Title: STYDY OF SINGLE AND MULTI-WALLED NANOTUBES BY SCANNING TUNNEL SPECTROSCOPY
Authors: Z.Y.Kosakovskaya, V.A.Vdovenkov, V.V.Kolesov, A.L.Kosakovskaya
Affiliations: Institute of Radio Engineering and Electronics of RAS
Abstract:
The conductivity of single and multi-walled larger diameter carbon nanotubes was studied by STS method. The subject of our investigation was nanotube film on n-Si substrate. STM studies shown that the film consist of mixture single nanotubes with diameter 1.03 – 1.7 nm and multi-walled nanotubes having diameter more than 8 nm, which were normal oriented to silicon substrate surface. It was find that STS I-V characteristics gualitatively depends on nanotube’s diameter. I-V of multi-walled nanotubes seems as monotonous I-V of rectification junction. Correspondence characteristics for single nanotubes contains steps, distance between each other depends on nanotube hirality. At room temperature dI/dV characteristics appears additional peak distance from each other on multiple to 60 or 125 meV. It is very interesting, that these energies coincide with energies of typical IR-reflection bands. We connect these peculiarity of I-V characteristics with structure of electron state density in nanotubes.
Dr. Zoia Yaroslavovna Kosakovskaya
Institute of Radio Engineering and Electronics of RAS
Mokhovaya, 11
Moscow, 101999
Russia
7-095-2033689 (phone)
7-095-2038414 (fax)
------------------------------------------------------------
Title: MAGNETORESISTANCE OF WELL-ORIENTED CARBON NANOTUBE FILMS.
Authors: Z. Kosakovskaya, V.Vdovenkov, Y.Gulyaev, A.Korovin, T.Kolesnikova, A.Kosakovskaya
Affiliations: Institute of Radio Engineering and Electronics of RAS
Abstract:
In our work we studied magnetic properties of well-oriented single and multi-walled carbon nanotube films on qurtz and YAG substrates, which were synthesized by electron-beam method [1]. It was shown, that the nanotube films have diamagnetic nature similar graphite (nanotube film was pushed out by magnetic field). Magnetoresistance of nanotube films at different orientation nanotube concerning a direction of magnetic field was investigated. It was obtaned, that the magnetoresistance of nanotube film depends on orientation nanotube in magnetic field and changes very much.. We observed that the nanotube films has the memory about initial influences of magnetic field (0.2 Tl). This magnetic memory is different for single and multi-walled nanotubes. The relaxation time of nanotube magnetoresistance is more than month. Observably anomalies of magnetic behaviour of nanotube films we attribute the one-dimensional character of nanotube structure and the manifestation of quantum effects of transport a charge. The study of magnetic properties of carbon nanotube films is shown the perspective this material for sensors of magnetic field 1. Kosakovskaya Z.Ya. JETP Lett. 1992, v.56, N1,pp.26
Prof. Alla Andreevna Novakova
Moscow M.V.Lomonosov State University, Department of Physics
117234 Moscow, Vorobiovi Gori
Moscow, 1172234
Russia
7(095)939 1226 (phone)
7(095)932 8820 (fax)
------------------------------------------------------------
Title: Diagnostics Of The Raw Powders Produced By Catalytic Carbon Arc Sputtering Method
Authors: Novakova A.A.*, Tarasov B.P.**, Kiseleva T.Yu.*
Affiliations: *Moscow M.V.Lomonosov State University, Department of Physics; **Institute for New Chemical Problems RAS, Russia
Abstract:
To study the both wall soot and deposits (black core and outer hard shell) powder samples obtained by catalytic arc method with Fe-catalyst powder (10 wt%) we used magnetic measurements and Mossbauer spectroscopy. This method is very sensitive to the chemical and structural environment of iron atoms on a nearest-neighbor length scale and therefore allows the chemical and magnetic structure of small iron particles to be analysed as well as their size and volume. We have found that the phase composition and magnetic properties of the samples depend considerably on their formation place in the chamber. The black core of deposit and wall soot are mostly diamagnetic. As it's well known they contain many carbon nanotubes and that's why we consider their single line spectrum (with parameters corresponding to iron ultrafine particles bounded with activated carbon)as iron-catalytic centers connected with nanotubes. The light and grey outer hard shell products which are known to contain many iron nanoparticles are ferromagnetic. The main component in their Mossbauer spectra is six-line pattern. Analysis of the spectral components relative intensities showed that the ratio of iron-catalytic centers connected with nanotubes to iron nanoparticles is higher in gray hard outer shell than in the light one.
Dr. Nikolaj Gennad'evich Lebedev
Volgograd State University
Physical faculty
ul. 2-ja Prodol'naja, 30
Volgograd, 400062
Russia
007-8442-448198 (phone)
(fax)
------------------------------------------------------------
Title: Pseudo-spine formalism for Hubbard model of single-walled carbon nanotubes
Authors: M.B.Belonenko, N.G.Lebedev
Affiliations:
Abstract:
For Hubbard model of single-walled carbon nanotubes (SWCN) we develope the 3/2 pseudo-spine formalism to study pseudo-spine dynamics in tubes. Two-band Hubbard model with repulsion of electrons at site has been proposed. Hubbard hamiltonian is easy transformed to pseudo-spine one by using matrix representation of Fermi operators and the continual approximation. The movement equations of pseudo-spine were obtained. The derived equations allow the solitons solutions for spine variables.
Dr. Valery A. Luchnikov
Institute of Chemical Kinetics and Combustion
3, Institutskaya str.
Novosibirsk, 630090
Russia
+7-3832-332854 (phone)
+7-3832-342350 (fax)
------------------------------------------------------------
Title: Molecular Dynamics simulation of nanotube fabrication from strained heterostructures.
Authors: Luchnikov V.A.
Affiliations: Institute of Chemical Kinetics and Combustion, 630090, Novosibirsk, Russia
Abstract:
Recently a new nano-objects fabrication method, based on bending of strained heterostructures, has been reported by Prinz et al [1]. We present Molecular Dynamics simulation of nanotube formation, performed in this technique. The heterostructure is modelled by two layers of different atoms, arranged in the face-centered cubic lattice. Interatomic forces are determined by the Lennard-Jones potential with the parameters specific for each type of atoms. The equilibrium bulk lattice constant for the atoms of the top layer is set several percents smaller than for the bottom layer. Initially, the bilayer is kept flat by interaction with the substrate. Etching of the sacrificial layer of the substrate is simulated by the time and co-ordinate dependent potential of interaction between the atoms of the substrate and the atoms of the bilayer. The potential is smoothly switched off from the right to the left end of the model, and the unfettered part of the bilayer scrolls up under the moment of force. The dependence of the tube diameter on the lattices mismatch and the bilayer thickness are studied. The modelling of nanotube formation is visualized by computer animation. It is planned to present MD simulation of GeSi/Si nanotube fabrication with the Tersoff potential and consider the influence of surface reconstruction effects. [1] V.Ya.Prinz et al, Physica E 6 (2000) 828-831
Dr. Emma Mogilko
Bar-Ilan University

Ramat-Gan, 52900
Israel
+972 3 5318432 (phone)
+972 3 5353298 (fax)
------------------------------------------------------------
Title: Carbon - metal composite nanoparticles produced
Authors: O.Prilutsky^{1}, E.Mogilko^{2}, Yu.Kaganovskii^{2}, Y.Schlesinger^{2}
Affiliations: ^{1}Ofakim Initiative Technologies, POB 633, Ofakim 80300, Israel, ^{2}Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel
Abstract:
Morphology of carbon nanoparticles produced by disproportionation of carbon monoxide at Fe, Ni and Co catalysts have been studied by TEM and AFM methods. The nanoparticles have been grown at 540 - 600oC; the reaction rates using different catalysts varied about by one order of magnitude. Under identical temperature and other synthesis conditions, the reaction rate per unit catalyst mass was the lowest with Ni, 3 - 5 times higher with Co, and 8 - 10 times higher with Fe as catalyst. Two main types of nanoparticles were observed at various reaction rates: nanospheres (onions) and nanotubes. The diameter of the spherical nanoparticle varied from 10 to 100 nm and contained a core of catalyst nanoclusters. The nanotube diameter varied from 10 to 100 nm and the length varied from 0.1 to 2 mm. Nanotubes contained spherical nanoparticles of catalyst at the end or in the middle of the tubes. With the increase of the reaction rate nanotubes of Y- and T-type shape have been sometimes detected, and the fraction of Y- and T-type nanotubes became larger with the increase of the reaction rate. Sedimentation analysis of the reaction products was carried out. On the basis of the morphology observation at various reaction rates and processing times, we propose a model of the nanotube growth.
Dr. Nikolaj Gennad'evich Lebedev
Volgograd State University
Physical faculty
ul. 2-ja Prodol'naja, 30
Volgograd, 400062
Russia
007-8442-448198 (phone)
(fax)
------------------------------------------------------------
Title: An estimation of piezoelectric modules of carbon and boron nitride nanotubes
Authors: N.G. Lebedev, I.V. Zaporotskova, L.A. Chernozatonskii
Affiliations:
Abstract:
We present the attempts to evaluate some piezoelectric modules of carbon (C) and boron nitride (NT) nanotubes (NT) by first principles. Ahiral small diameter nanotubes were considered for the purpose. The molecular cluster model in MNDO approach was applied to simulate geometry structure and to calculate energy characters of NTs. The quantum chemical calculations of NT polarization in accordance with the stretch of NTs along axis have allowed estimate the piezoelectric constants values of small diameter C- and BN-NTs. We have obtained following results (for instance): C-NT (5,5): Exx= 0.33 mCl/m2; BN-NT (5,5): Ezz = 0.01; Dzz = 0.07 pCl/Pa m2; Exx= 0.33; BN-NT (6,6): Ezz = 0.04; Dzz = 0.16; BN-NT (6,0): Ezz = 9.0; BN-NT (7,0): Ezz = 8.5. The analysis of obtained results has shown the general tendency to increase the piezoelectric constant values in accordance with the rise of NT diameter for BN-NT (n,n). In contrast last the piezoelectric constant values are decreasing with the rise of diameter for BN-NT (n,0).
Dr. Nikolaj Gennad'evich Lebedev
Volgograd State University
Physical faculty
ul. 2-ja Prodol'naja, 30
Volgograd, 400062
Russia
007-8442-448198 (phone)
(fax)
------------------------------------------------------------
Title: Indirect interactions of d-spins via phonons in carbon nanotubes
Authors: M.B. Belonenko, V.V. Diakov, N.G. Lebedev
Affiliations:
Abstract:
Well-known that d- and f-metals are able to fill carbon nanotubes. So we are interesting to consider the question about interaction of d- and f-implants with phonon fields. Hamiltonian of studying system is given by unperturbed Hamiltonian consisting from free spin and phonon operators and Hamiltonian of interaction between spines and phonons. In creation of interaction Hamiltonian we consid-ered that the oscillation of atom leads to the crystal polarization. We calculated the indirect interaction of spins by Frohlich method. The coefficients of exchanged interaction were obtained. The effective radius of in-direct interaction is analyzed. The temperature dependencies of exchanged coefficients are studied.
Dr. Igor Bazhin
Don Technical University
Gagarin Sq. 1
Rostov-on-Don, Rostov Region 344010
Russia
(8632)713305 (phone)
(fax)
------------------------------------------------------------
Title: Different structures of polymerized fullerenes
Authors: I.V.Bazhin, A.P.Popov
Affiliations: Dept. of Physics, Don State Technical Univercity
Abstract:
Ever since solid C60 was discovered this phase of crystalline carbon has been studied very intensively. Well known the high pressure applied to solid C60 at high temperature induce polymerization of C60. There observed three distinct phases [1-5] with quasi one-dimensional (linear chains) and quasi two-dimensional (planar) structures. In this paper the possibility of the existence of the other structures of polymerized fullerenes is investigated. In quasi one-dimensional case we investigate not only line chains but also the formation of ring structures of polymerized C60 and C76. In three-dimensional case we study the possibility of formation of cubic phase of solid C60, C76 and C92. The different approaches (empirical Tersoff-Brenner formalism, methods of quantum chemistry as semiempirical AM1, PM3, MNDO and so ab initio methods) lead to similar results and conclusions: all the structures are stable and can exist. The parameters of the structures and energy of the bonds are calculated. Some elastic and electronic properties of the structures are predicted. 1. Y.Iwasa et al., Science, 264,1570,1995 2. M.Nunez-Reguero, L.Marques, J-L.Hodeau, O.Bethoux, M.Perroux, Phys.Rev.Lett.,74,278,1995 3. G.Oszlanyi, L.Forro, Solid State Commun., 93, 265, 1995 4. C.H.Xu, G.E.Scuserio, Phys.Rev.Lett., 74, 274, 1995. 5. S.Okadi, S.Saito, Phys.Rev.B, 55, 40
Dr. Alexand Popov
Don Technical University
Gagarin Sq. 1
Rostov-on-Don, Rostov Region 344010
Russia
(8632)381516 (phone)
(fax)
------------------------------------------------------------
Title: Interaction of carbon nanotubes with molecules and substrates
Authors: A.P.Popov, I.V.Bazhin
Affiliations: Dept. of Physics, Don State Technical Univercity
Abstract:
The purpose of the paper is investigation of the carbon nanotubes with attached molecules and nanotubes adsorbed by the crystal surfaces. To found the equilibrium geometry the method of molecular dynamics in framework of the widely effective many-body Tersoff-Brenner potential [1-2] was used. The electronic and chemical properties of the products on a basis of nanotubes were received using quantum chemistry methods. Quantum chemistry simulations were carried out using semiempirical (PM3) and ab initio RHF (STO-3G and 3-21G) methods. For testing the methods the products of benzyne addition to naphthalene, anthracene and nanotube were calculated. Our results are in good agreement both with experiment and with earlier calculations [2]. Results of interaction of a nanotube and substrate were received for two cases. In the first case the nanotube is towered as a column above a surface, in the second case construction is similar to a cricket gate. The computational experiment has clearly shown that the open nanotube can be connected to the crystal surfaces by one of the free edges. The binding energy for (6,0)-tube with graphite (0001) surface is about 8.3 eV. The same computational simulation has shown also that the open bent nanotube can be connected to the crystal surfaces by both free edges. It is necessary to notice that the bent nanotube possesses the significant positive energy but the construction is metastable due to the energy barrier about 4.6 eV which must be overcomed for the transition to the ground state. 1. Garg A., Sinnott S.B., Nanotechnology 10, 273 (1999) 2. Jaffe R.L., Smith G.D., J. Chem. Phys, 105, 2780 (1996)
Dr. Sergey B Nurmagambetov
Karaganda State University
P.O. Box 26
Karaganda, 470074
Kazakhstan
(3212) 756934 (phone)
(fax)
------------------------------------------------------------
Title: Angular Disrtibution of Electron Beams Channeling in Nanotubes
Authors: S.B.Nurmagambetov
Affiliations: Karaganda State University
Abstract:
The nanotubes are a natural channel for the propagating of the relativistic particle beams. In contrary to axe channeling when channeling particle is scattered by crystallographic axe in beam direction nanotube channeling has special azimutal symmetry. This symmetry is depended from nanotube structure and thus we can see this structure in angular distribution of relativistic electron beams that move through nanotube. In paper we present our results of the investigation the dependences of nanotubes structure with angular distribution types for various energy of electron beams.
Prof. Yurii Mironovich Volfkovich
Frumkin Institute of Electrochemistry
Leninskii prospect 31
Moscow, 117071
Russia
7-095-9554019 (phone)
7-095-9520846 (fax)
------------------------------------------------------------
Title: Electrochemical generation and oxidation of hydrogen in carbon nanomaterials of attested porous structure
Authors: Yu.M. Volfkovich a, O.N. Efimov b, B.P. Tarasov b, A.Yu. Rychagov a,
Affiliations: a A.N. Frumkin Institute of Electrochemistry, 31 Leninskii Prospect, 117071 Moscow, Russia;b
Abstract:
The porous structure of carbon nanomaterials (CNM) was investigated by the Method of Standard Porosimetry (MSP) [1] and Raman Spectroscopy (RS). The single wall carbon nanotubes (SWNTs) utilized in the present study were prepared by the arc-discharge technique using a Co/Ni catalyst. According to RS, the tubes have diameters from 1.2 to 1.8 nm. The SWNTs have been exhaustively depleted of acid-soluble cobalt and nickel particles, and purified to ca. 70 wt. % tube content by air-oxidation technique which ensures opening of tubes. As determined by MSP, the specific volume of the internal channel of these SWNTs is equal to 0,29 cm3/g. The specific adsorption of hydrogen in SWNT is 3,5 wt. % at 3 MPa hydrogen pressure and room temperature. Hence density of hydroge is 0,12 g/ñm3, which value surpasses the liquid hydrogen density (0,07 g/ñm3) by a factor of 1.7. It implies the extraordinary strong attraction between hydrogen molecule and internal tube surface. The SWNTs and "edge-abundent" carbon nanofibers of high purity, 70 and 95 wt. %, accordingly, were used for a detailed study of their electrochemical behavior in 1N H2SO4. A double layer supercapacitor with electrodes containing these CNM was built and explored. A reversible peaks were found at E ~ - 0.2 V RHE on cyclic chrono-voltammetry curves for SWNT electrode. The appropriate capacity of the SWNT electrode is 60 C/g. The peaks pertains to electrochemical generation-electrooxidation of hydrogen and its adsorption-desorption inside SWNTs. No distinct reversible peaks were observed for carbon nanofibers studied. References 1. Yu. M.Volfkovich, V.S.Bagotzky, J. Power Sources, 48 (1994) 327, 339.
Dr. Nikolaj Gennad'evich Lebedev
Volgograd State University
Physical faculty
ul. 2-ja Prodol'naja, 30
Volgograd, 400062
Russia
007-8442-448198 (phone)
(fax)
------------------------------------------------------------
Title: Elastic modules of carbon and boron nitride nanotubes in a molecular cluster model
Authors: N.G.Lebedev, L.A.Chernozatonskii, I.V.Zaporotskova
Affiliations:
Abstract:
In the given article the results of calculasion of elastic characters of carbon (C) and boron-nitride (BN) nanotubes (NT) are represented with the purpose of study of mechanical properties of these by quantum-chemical scheme MNDO. As NT models the molecular clusters (MC) in which the border bondings satu-rated by hydrogens were selected. We have obtained the following results (for in-stance): C-NT (5,5): ?=0.15 GPa, s=0.22, ?11=0.17 GPa, ?12=0.05 GPa, ?66=0.06 GPa; C-NT (6,6): ?=0.19 GPa, s=0.22, ?11=0.22 GPa, ?12=0.06 GPa, ?66=0.08 GPa; BN-NT (5,5): ?=0.12 GPa, s=0.35, ?11=0.19 GPa, ?12=0.10 GPa, ?66=0.04 GPa; BN-NT (6,6): ?=0.15 GPa, s=0.34, ?11=0.23 GPa, ?12=0.12 GPa, ?66=0.05 GPa.; where ? – Young’s modulus, s – Poisson ratio, C – elastic modules. These magnitude were calculated by curves of potential energy of processes of tubes strain along their axes. The analysis of results obtained for C- and BN-NT (n, n)-type (n=5..., 9) shows a general tendency of magnification of the Young’s module E and elastic constants with increasing of a diameter of tube. The opposite picture is observed in BN-NT (n, 0)-type for (n=6..., 10). For BN-NT (6,0) E=0.71 GPa; for BN-NT (7,0) E=0.61 GPa. In this case the diminishion of the module E happens to magnification of diameters of one.
Dr. Nikolaj Gennad'evich Lebedev
Volgograd State University
Physical faculty
ul. 2-ja Prodol'naja, 30
Volgograd, 400062
Russia
007-8442-448198 (phone)
(fax)
------------------------------------------------------------
Title: OSC-model of process of carbon nanotubes generetion on quantum dots of diamond surface
Authors: N.G.Lebedev, I.V.Ponomareva, A.O.Litinskii, L.A.Chernozatonskii
Affiliations:
Abstract:
The orbital-stoihiometric cluster (OSC) model is applied to simulate the diamond surface in order to study of carbon nanotube generation process using quantum chemical MNDO-scheme. In this model the cluster base includes all atom orbitals of internal atoms. The border atoms bring in the base only sp3-hybrid orbitals directed inside of cluster. OSC-model was successfully applied to study an electronic structure of covalent crystals and their surfaces. We have carried out the calculations of energy characters of processes of carbon atom connecting to diamond surface, of carbon atom connecting in presence of lithium, sodium, potassum atoms. Atom by atom the polihen rings for all considered cases were constructed on diamond surface. The calculated potential energy surface have allowed to make following conclusions: 1. In the presence of quantum dots the process of carbon atom adsorbtion runs already at normal temperature. 2. The process of further growth of carbon nanotubes speeds up on the quantum dots.
Dr. Nikolaj Gennad'evich Lebedev
Volgograd State University
Physical faculty
ul. 2-ja Prodol'naja, 30
Volgograd, 400062
Russia
007-8442-448198 (phone)
(fax)
------------------------------------------------------------
Title: On the tensor of conductivity of single-walled carbon nanotubes
Authors: M.B.Belonenko, V.V.Grachev, N.G.Lebedev
Affiliations:
Abstract:
In spite of variouse publications in scientific press the problem of studying the conductivity properties of single-walled carbon nanotubes (SWCN) has been the object of much concentrated attention of theorists and experimentators. We have the pleasure of bringing to your notice the investigation of SWCNs conductivity. For this aim the two-band Hubbard model with repulsion of electrons at site hes been proposed. Using Green's functions formalism we have arrived at correlation relations for two-particle fermi operators that allows to obtain the formula of conductivity tensor of SWCNs. The obtained term has cleary shown the temperature dependence behaviour of SWCNs conductivity.
Prof. Oleg V. Kibis
Novosibirsk State Technical University
Karl Marx avenue 20
Novosibirsk, 630092
Russia
+7 3832 460488 (phone)
+7 3832 460209 (fax)
------------------------------------------------------------
Title: An asymmetry of electron properties of chiral carbon nanotubes in a magnetic field
Authors: O. V. Kibis
Affiliations: Novosibirsk State Technical University, Novosibirsk 630092, Russia
Abstract:
Low-dimensional structures with simultaneous breaking of time-inversion symmetry and spatial-inversion symmetry have an asymmetrical electron energy spectrum \(epsilon)(k)\neq\(epsilon)(-k) , where k is electron wave vector. As consequence, its electronic properties are different (asymmetrical) for mutually opposite directions, and because of it new electron phenomena appear. These phenomena were predicted in [1–2] for two-dimensional structures and observed there in recent experiments [3]. In the presented study for the first time it shows theoretically that these phenomena take place also in chiral carbon nanotubes in presence of magnetic field. Really, in nanotubes due to its chiral crystal structure a spatial-inversion symmetry is absent and due to magnetic field there is breaking of time-inversion symmetry. The analysis, which based on modified tight-binding model of nanotube [4], result in existence of a photovoltaic effect and an effect of rectification of electrical current there. The work is supported by Russian foundation for basic research (Grants #00-02-17987, #00-02-18010 and #01-02-99305), Russian ministry of education (Grant #2000-3-506) and INTAS (Grant #99-1661). [1] O.V. Kibis, Phys. Lett. A 237 (1998) 292 [2] O.V. Kibis, Phys. Lett. A 244 (1998) 432 [3] A.G. Pogosov, M.V. Budantsev, O.V. Kibis, et al., Phys. Rev. B 61 (2000) 15603 [4] D.A. Romanov, O.V. Kibis, Phys. Lett A 178 (1993) 335
Prof. Karo Asatour Ispirian
Yerevan Physics Institute
Brothers Alikhanian 2
Yerevan, 375036
Armenia
(3741) 34 46 98 (phone)
(fax)
------------------------------------------------------------
Title: Possible Applications of Carbon Nanotubes in High Energy Physics
Authors: K.A.Ispirian
Affiliations: Yerevan Physics Institute, Yerevan, Armenia
Abstract:
Taking into account the advantageous properties of single and wall nanotubes (SWNT) compared with those of single crystalls, a review of the theoretical results on high energy particle channeling, channeling radiation, bending, focusing and acceleration in SWNT is given. Since the existing data show good field emission characteristics of nanotubes in constant electric fields their use as high current cathode emitters providing low emittance beams in RF guns is considered. The requirements for such applications are discussed.
Ms. Alexander A. Mozelev
Radical
Ring Str. 1
Friedrichsdorf, Hessen 61381
Germany
49-172-4919696 (phone)
(fax)
------------------------------------------------------------
Title: IMPROVED COMPACT X-RAY SOURCES FOR NANOTECHNOLOGIES
Authors: A. Mozelev
Affiliations: Dr.
Abstract:
IMPROVED COMPACT X-RAY SOURCES FOR NANOTECHNOLOGIES A. Mozelev Small Scale Research and Production Company RADICAL Ring Str.1 61381 Friedrichsdorf, Germany Electron and ions acquire a high energy and produce X-rays with a relatively high efficiency by interaction with different materials. In this work, a principally new source using a radiation generator is proposed. The remote handling of physical parameters (intensity, energy of gamma quants, etc.) makes it possible to use a gamma quant generator in different area of science and technique. The designing of the generator was intended for the most difficult application case-a deep borehole with high temperatures and high pressure. It was necessary to minimize dimensions and the power the generator needed and this has resulted in the minimum possible impulse duration. As a result of the researches the following parameters have been received Diameter less than dotfill 70 mm Length less than dotfill 300 mm Weight less than dotfill 2 kg Electron source specification: Kinetic energy dotfill 500 KeV Pulse duration dotfill 10 ns Impulse frequency dotfill 0.5 -- 50 Hz. Using a high- speed detector in the couple, X-ray generator can be used for research in namotechnologies and defectoscopy of borehole casing columns, rock density measure, etc.
Dr. Sergiy N. Dobrovolsky
N.S.C. "Khärkov Institute of Physics and Technology"
Akademicheskaya str., 1
Kharkov, Kharkov 61108
Ukraine
+380572 356462 (phone)
+380572 352683 (fax)
------------------------------------------------------------
Title: TRANSITION RADIATION OF RELATIVISTIC ELECTRONS ON THE NANOSTRUCTURES
Authors: Dobrovolsky S. N., Shul'ga N. F., Syshchenko V. V.
Affiliations: National Scientific Center "Kharkov Institute Physics and Technology", Belgorod State University, Belgorod, Russia
Abstract:
Recently we called attention to the fact that target's transverse geometry (transversal size and shape of target) can strongly influence to the transition radiation intensity of relativistic electrons in the thin targets [N.F. Shul’ga, S.N. Dobrovol’skii, JETP. 90 (2000) 579; Phys. Lett. A 259 (1999) 291]. In this paper the problem of transition radiation by relativistic electrons on the nano-structures (nanotubes, fullirens) is investigated. So, we've showed that in the some regions of waves, the spectral-angular characteristics of transition radiation are depending from transversal size and shape of nano-target. The strong decreasing of intensity and spreading of angular distribution of radiation can occur. In the region of radiated waves, where \{lambda} \geq a \div (division)\{gamma} (a - effective transversal size of target, \{gamma} - Lorenz-factor of electron) this effect is strongly appeared. The obtained results point to the possibility of using transition radiation of electrons for the diagnostics of nano-structures. This work is partially supported by INTAS Project #97-30392 and grant of RFFI #00-02-16337.
Prof. Nikolai F. Shul'ga
Institute for Theoretical Physics NSC KIPT
Academichna Str.1
NSC KIPT
Kharkov, 61108
UKRAINE
38-0572-356462 (phone)
38-0572-352683 (fax)
------------------------------------------------------------
Title: MOTION AND SCATTERING OF FAST CHARGED PARTICLES IN NANOTUBE FIELD
Authors: N.F. Shul’ga, A.A. Greenenko, V.I. Truten’, S.P. Fomin
Affiliations: Institute for Theoretical Physics NSC KIPT, Kharkov 61108, Ukraine ; Belgorod State University, Belgorod 308007, Russia
Abstract:
It is considered a problem of fast charged particle motion and scattering in nanotube field for the case of small angle between particle momentum and nanotube axis direction. In many respects, this problem is similar to the problem of fast particles motion in oriented crystal [1]. For this reason, it is possible to use the methods, which are well known in the theory of particle passage through crystals, for description of fast particle motion in nanotube. On the base of this analogy, the problem of particle motion in continuous nanotube potential is studied. Scattering of electrons and positrons by nanotube is examined in approximation of radial symmetrical continuous nanotube potential. The possibility of rainbow scattering and orbiting effects for this case is shown. Influence of nanotube potential inhomogeneity on particle motion is considered too. It is shown, that charged particle motion in nanotube field may be both regular and chaotic. Possibility of above-barrier positively particles capture to regime of pseudo-channeling is demonstrated. The work is partly supported by projects INTAS 97-30392 and RFFR-00-02-16337. [1]. A.I. Akhiezer, N.F. Shul'ga, V.I. Truten', A.A. Greenenko, V.V. Syshchenko, Phys. Uspekhi 38(10) (1995) 1119.
Dr. Vladislav V. Syshchenko
Belgorod State University
Studencheskaya st., 12
Belgorod, 308007
Russian Fedration
0722-340587 (phone)
(fax)
------------------------------------------------------------
Title: On the transition radiation of relativistic charged particles on atomic strings of a crystal and in the field of nanotubes
Authors: N.F.Shul'ga, V.V.Syshchenko
Affiliations: National Science Center Kharkov Institute of Physics and Technology; Belgorod State University
Abstract:
The problem of transition radiation under impact of heavy relativistic particles (protons, \{pi}-mesons etc.) under small angle to the atomic string of a crystal and to the nanotube is considered. The conditions under which the non-uniformity of the electron density along the string (nanotube) is not substantial are obtained. In this case the problem of transition radiation is reduced to the problem about the particle radiation on the fiber-like target with \{delta}-like density distribution in transverse plane. The formulae for the spectral-angular distribution of transition radiation under both regular and random collisions of a particle with a set of fiber-like targets are obtained. The consideration of the radiation process is carried out in the frames of perturbation theory on the interaction of the particle with fiber-like target. This work is supported in part by INTAS (project 97-30392), Russian Foundation for Basic Research (project 00-02-16337), and Ministry of Education of Russian Federation (project 97-0-143-5).
Mr. Abdelaazi RADOUA
Faculté des Sciences
BP 28/S
Agadir, 80000
Morocco
212 08 22 09 57 (phone)
212 08 22 01 00 (fax)
------------------------------------------------------------
Title: Study of the photorefractive effect in electro-optics crystals
Authors: A. Radoua, M. A. Ouabbou, L. Lifsal, D. Khatib
Affiliations: Laboratoire de Physique du Solide Théorique, Département de Physique, Faculté des Sciences,
Abstract:
In the present contribution we shall confine our attention to the photorefractive properties of the electo-optic crystals. Photorefractive crystals are of special interest for many advanced and promising applications. The photorefractive effect is the transformation of a light pattern into a refractive index pattern in an electro-optic crystals. In bright regions, usually created by constructive interference of coherent light beams, defects are photoionized, and the resulting quasifree charge carriers are transported to new trapping sites. The resulting space charge pattern is transposed into a refractive index pattern by the electro-optic effect.Photorefractive properties of electro-optics crystals are calculated as a function of many physics parameters (fringe spacing, intensity, applied electric field...). It is found that the application of an electric field influences the charge transport and leads to an increased space charge field. Therefore, leads to a considerable coupling gain. The behavior is calculated in terms of a transport model including deep and shallow traps.
Dr. Irina Vladimirovna Zaporotskova
Volgograd State University
2-ya Prodolnaya, 30
Volgograd,
Russia
43-35-56 (phone)
(fax)
------------------------------------------------------------
Title: To the question about hydrogenization of carbon nanotubes.
Authors: Zaporotskova I.V., Lebedev N.G., Chernozatonski L.A.
Affiliations:
Abstract:
To the question about hydrogenization of carbon nanotubes. Zaporotskova I.V., Lebedev N.G. Volgograd State University, 2-ya Prodolnaya, 30, Volgograd, Russia Chernozatonski L.A. Institute of Biochemical Physics of RAS, 117334 Moscow, Russia Despite of rather active development of a question of hydrogenization of carbon nanotubes to the present time there are still insufficiently well investigated features of process of connection of atomic hydrogen to the surface (internal and external) of a small diameter nanotubulens. Represented work is devoted to consideration of this problem. By the purpose of the carried out researches was the consecutive quantum-mechanical study within the framework of the calculated scheme MNDO and both models molecular and ion-built and covalent-cyclic clusters the influences of atoms ?, which adsorbed on external and internal surfaces of single-walled carbon nanotubes such as "arm-chair" to geometry of tubulen, study of distortions of structure caused by these atoms, and also accounts the energies of adsorption with the purpose of definition and specification of the most favourable situations of adatoms of hydrogen. The executed accounts have found out the following: a) is possible the adsorption of atoms ? on the nearest atoms of carbon of the tubulen surface. b) hydrogenization of tubulen causes deformation of nanotube`s surface and partial infringement of its cylindrical symmetry. The surface adsorption results in occurrence besides external also internal active centre, providing an opportunity external and internal adsorption simultaneously; c) multiple external adsorption (the chain of atoms ?) on semyendless nanotube also causes its deformation. Alternating through one in the chain the carbon atoms of surface behave differently: one rise above the surface, others - leave deep into tube.
Dr. Yuriy Ivanovych Prylutskyy
Kyiv National Shevchenko University
Faculty of Biology, Dept. of Biophysics
Volodymyrska Str., 64
Kyiv, 01033
Ukraine
+380 44 266 22 76 (phone)
+380 44 252 0827 (fax)
------------------------------------------------------------
Title: Structure, Electronic and Optical Properties of Carbon Nanotubes under Irradiation
Authors: M.P. Kulish^{1}, O.P. Dmytrenko^{1}, and Yu.I. Prylutskyy^{2}
Affiliations: Kyiv National Shevchenko University, Dept. of ^{1}Physics and ^{2}Biophysics, Volodymyrska Str., 64, 01033 Kyiv, Ukraine
Abstract:
It is known that the irradiation of matter by particles is the effective method for creation of materials and devices with new properties. Due to the unique physical properties [1] the single-walled carbon nanotubes (SWCNT) are looked upon as promising candidates for nanotechnology. In present report we have considered the following problems in detail: the mechanism of interaction of low- and high-energy particle (electron and phonon beams) with SWCNT; the spatial distributions of electronic exitations and ionization of atoms, projectiles and energy losses, irradiation defects and kind of theirs; the linear and third-order nonlinear polarizabilities of SWCNT, their vibrational and electronic spectra. Several methods (electron microscopy, micro- and X-ray diffraction, IR, Raman, UV-VIS and scanning tunneling spectroscopy, ellipsometrical and third-harmonic-generation measurements) were used to study the structure, electronic and optical properties of SWCNT under irradiation, as well as properties of their electron systems and their interaction with the media. The experimental studies were supported by the theoretical calculations within the molecular dynamics and quantum chemistry tight-binding and semi-empirical PM3 methods [2]. [1] R. Saito, et al., Physical Properties of Carbon Nanotubes, Imperial College Press (1998). [2] Yu.I. Prylutskyy, et al., Comput.Mat.Sci. 17 (2000) 352.
p>
Dr. Yuriy Ivanovych Prylutskyy
Kyiv National Shevchenko University
Faculty of Biology, Dept. of Biophysics
Volodymyrska Str., 64
Kyiv, 01033
Ukraine
+380 44 266 22 76 (phone)
+380 44 252 08 27 (fax)
------------------------------------------------------------
Title: Effect of pressure on the lattice dynamics of carbon nanotubes
Authors: Yu.I. Prylutskyy^{1}, O.V. Ogloblya^{2}, and P. Eklund^{3}
Affiliations: Kyiv National Shevchenko University, Dept. of ^{1}Biophysics and ^{2}Physics, Volodymyrska Str., 64, 01033 Kyiv, Ukraine, ^{3}Penn State University, Dept. of Physics, University Park, PA 16802-6300, USA
Abstract:
The structure and lattice dynamics of the single-walled carbon nanotubes (SWCNT) as functions of axial compression of the nanotube were studied in detail. To obtain the phonon dispersion relations and the polarization vectors for the SWCNT we take into account that the nanotube is quasi-1D system and the potential energy of the nanotube lattice includes only two contributions [1]: a central force, which depends on the distance between two neighbouring carbon atoms, and the force is due to the bond-bending between the atoms. Two parameters of this model were determined by fitting them to the experimental data on the measurements of elastic properties of SWCNT [2]. The phonon spectrum, sound velocities and elastic constants for the SWCNT were calculated and analyzed in dependence on their symmetry. The theoretical results obtained were compared with the acoustic spectroscopy data. This work was partly supported by the CR NATO grant. Authors thank Dr. S. Fang (University of Kentucky, USA) for kindly providing the SWCNT samples. [1] Yu. Prylutskyy, et al., Mol.Mat. 13 (2000) 71. [2] E.W. Wong, et al., Science 277 (1997) 1971.
Dr. Irina Vladimirovna Zaporotskova
Volgograd State University
Physical faculty
ul. 2-ja Prodol'naja, 30
Volgograd, 400062
Russia
007-8442-468419 (phone)
(fax)
------------------------------------------------------------
Title: The investigation of processes of fluorination and oxidation of carbon nanotubes
Authors: I.V.Zaporotakova, N.G.Lebedev, L.A.Chernozatonskii
Affiliations:
Abstract:
The simple molecular cluster model within the framework of quantum chemical semiempirical sheme MNDO is applied for theoretical research of fluorination and oxidation of single-walled carbon nanotubes. The quantum–chemical calculations are carried out on an example carbon nanotubes (6,6)- and (10,0)-type. The unsaturated bondings on tube border completed by atoms of hydrogen. We carryied out the following variants of computation: 1) Connection from one to four fluorine or one oxygen atoms to surface carbon atoms along (6,6)-tube. 2) Adsorbtion from 1 to 6 atoms of O on carbon atoms around perimeter of (6,6). 3) Multiple adsorbtion af O on (10,0) For each variant the adsorbtion energy are received. It was found that the fluorine and oxygen atoms deform a carbon tube surface. Due to formation of chemical connections between F or O and carbon the electronic configuration of carbon atom changes: the atom passes from a sp2-hybrid station in a one closed to sp3-hybrid. We also investigated process of connection F and O to a tube surface, the potential energy of the given process is constructed.
Dr. Viktor E. Kaminskii
Institute of RadioEngineering and Electronics, RAS
Mokhovaya 11, bl.7, GSP-9
Moscow, 101999
Russia
(095)2033689 (phone)
(095)2038114 (fax)
------------------------------------------------------------
Title: AGNETOTRANSPORT IN CARBON NANOTUBES AND NEGATIVE MAGNETORESISTANCE
Authors: Viktor E. Kaminskii
Affiliations: Institute of RadioEngineering and Electronics, Russian Academy of Sciences
Abstract:
For density matrix the Liouville equation in effective mass approximation is solved in an arbitrary magnetic field for deformation acoustic scattering. Using density matrix off-diagonal components nanotube conductivity is calculated. If nanotube considered as effective conducting media it is shown that electron transport depends strongly on the ratio between nanotube diameter and magnetic length. If magnetic field is no very strong single-wall nanotube diameter is much less than magnetic length. For such conditions magnetic field can be considered as perturbation. In this case magnetoresistance is always positive. Band gap value determines its dependence on a magnetic field. For wide gap nanotube magnetoresistance depends approximately quadratic on a weak magnetic field. For narrow gap nanotube the spin-orbital interaction is very strong. It leads to the linear dependence on a weak magnetic field. Our results show that in nanotube the negative magnetoresistance can be described, at least partially, without theory of weak localization.
Dr. Anatolii S. Lobach
Institute of Problems of Chemical Physics RAS
142432 Chernogolovka, Moscow Region
, 142432
Russian Federation
096 522 33 93 (phone)
096 515 35 88 (fax)
------------------------------------------------------------
Title: EFFECT OF DIFFERENT EXPERIMENTAL CONDITIONS ON PURIFICATION OF SINGLE WALLED CARBON NANOTUBES
Authors: A.S. Lobach (1), N.G. Spitsina (1), E.D. Obraztsova (2), S.V. Terekhov(2)
Affiliations: (1) Institute of Problems of Chemical Physics RAS, 142432 Chernogolovka, Moscow Region, Russian Federation (2) Natural Sciences Center of General Physics Institute RAS
Abstract:
Here we present experimental data on purification of SWNT materials and the effect of different experimental conditions on purity of the resulting SWNT. These conditions are: heat pretreatment of raw material(RM); application and/or absence of acidic treatment of RM; time of oxidation of RM and concentration of oxidizing acid; dispersion of oxidized (non-oxidized) SWNT soot in different solvents; various modifications of microfiltration of a suspension of SWNT material: effects of a pore diameter of track-etched filter membranes; different temperature of additional oxidation in air; temperature and time of vacuum bake of SWNT. The content of SWNT was characterized by Raman scattering techniques on every stage. Optimal conditions of purification of SWNT are discussed. SWNT materials was synthesized by arc-discharge method with Ni:Y_2O_3:C (1:1:2) catalyst and contained 15-20 wt.% SWNT. The work was supported by RFBR (grant 00-03-32086, 01-02-17358a), by ISTC-1400 and by the Program "Fullerenes and Atomic Clusters".
Prof. Andrzej Huczko
Department of Chemistry
Pasteur 1
Warsaw, 02-093
Poland
048-22-8220211 (303) (phone)
048-22-8225996 (fax)
------------------------------------------------------------
Title: Hollow cathode glow discharge as a source for deposition of aligned nanocarbons
Authors: (1)H.Lange, (1)A.Huczko, (2)Y.Q.Zhu, (2)W.K.Hsu, (2)H.W. Kroto, (2)D.R.M.Walton, (3)P.Tomassi
Affiliations: (1)Department of Chemistry, Warsaw University, Pasteur1, 02093 Warsaw, Poland; (2)Fullerene Science Center, School of CPES, University of Sussex, Brighton BN1 9QJ, UK;(3)Institute of Precision Mechanics, Duchnicka 3, 00-967 Warsaw, Poland
Abstract:
Preliminary studies of non-equilibrium plasma deposition of carbon nanostructures on the anodic aluminium oxide (AAO) membrane with nanometer-scale channels are discribed, in order to obtain aligned nanocarbons. The membrane was placed inside the hollow cathode. The discharge was generating in He, Ar, or H_{2} gases, as well as ferrocene vapor, flowing through the membrane at pressure around 10 mbar. The homogeneous graphite hollow cathode, 5 mm diameter and 4 cm length, contains 0,8 at% Fe. Discharge current was {it\ca}. 40 - 120 mA. Optical emission spectroscopy (OES) was carried out to detect the carbon radicals(C_{2}, CH and CN), excited atoms and ions (e.g. FeI, ArII). Using C_{2} and CN bands (at 516,5 and 388,3 nm, respectively), we obtained the gas temperature varying from 150 to 300 ^{o}C. This result is significant in that the low temperature generation may overcome the main drawback of high temperature required ({it\ca}. 1000 ^{o}C) during thermal deposition of hydrocarbons for nanotube formation. SEM and TEM were used to characterize obtained depositions. The work was supported by the Committee for Scientific Research (KBN) through the Department of Chemistry, Warsaw University, under Grant No 3 TO9A 05816.
Dr. Oleg N. Efimov
Institute of Problems of Chemical Physics
Institutskii Str.18
Chernogolovka, Moscow region 142432
Russia
7-095-5227602 (phone)
7-095-5244401 (fax)
------------------------------------------------------------
Title: Electrophysical properties of composites based on polyacetylene and single-walled nanotubes
Authors: I.A.Tchmutin$^(a)$, A.T.Ponomarenko$^(a)$, E.P. Krinichnaya$^(b)$, L.I.Tkachenko$^(b)$, G.I.Kozub$^(b)$, O.N.Efimov$^(b)$,R.O. Loutfy$^(c)$, A.P. Moravsky$^(b,c)$
Affiliations: $^(a)$ Enikolopov Institute of Synthetic Polymeric Materials, RAS, Moscow, Russia,$^(b)$Institute of Problems in Chemical Physics, RAS, Chernogolovka, Russia, $^(c)$MER Corporation, Tucson, AZ, U.S.
Abstract:
The present work was aimed at the synthesis of composite materials based on polyacetylene and conductive filler, namely, SWNT and the study of their electrophysical properties in the 20-150$^o$ range. SWNTs used in the present study were prepared by the arc-discharge technique using a Co/Ni mixed catalyst (70 w/w. % tube content after purification). The tubes have diameters ranging from 1.2 up to 1.8 nm. Calculated density is equal 0.94 $g/cm^3$. Conductivity is equal to $1.2-1.7 10^3$ (Ohm cm)$^{-1}$. It was found that percolation threshold of polyacetylene- nanotubes composites is about 3 v/v.% and the composites with filler concentration higher than 6 v/v.% have conductivity of $10^{-1}$ - 100 (Ohm cm)$^{-1}$. For composites comprising 12 v/v/ % of nanotubes, conductivity is almost constant in the 20 - 110$^0C$ temperature range. The value of $\sigma(T)/\sigma(20^0C)$ grows up to 1.35 during heating from 110 up to 150$^0C$ and then increases up to 1.5 during cooling down to room temperature.
Mr. Géza I. Márk
Research Institute for Technical Physics and Materials Science
P.O.Box.49.
Budapest, H-1525
Hungary
(+36-20)340-7499 (phone)
(+36-1)392-2226 (fax)
------------------------------------------------------------
Title: Calculation of charge transfer in a carbon nanotube crossing
Authors: G. I. Márk(1,2), L. P. Biró(1,2), J. Gyulai(1), P. A. Thiry(2), and Ph. Lambin(2)
Affiliations: (1) Research Institute for Technical Physics and Materials Science, H-1525 Budapest, P.O.B. 49, Hungary; (2) Département de Physique, Facultés Universitaires Notre-Dame de la Paix, 61 Rue de Bruxelles, B-5000 Namur, Belgium
Abstract:
The perpendicular crossing of two carbon nanotubes on an insulating support may have interesting electrical properties which makes this geometry a potential building block for future nano-electronics. In this work, we calculated the transmission of an electron wave packet through the crossing of two carbon nanotubes by solving numerically [1] the three dimensional (3D) time dependent Schrödinger equation in a jellium model. The initial wave packet is launched along one of the tubes and the amount of charge tunneling into the other tube is studied as a function of the tube separation. G. I. Márk et al, Phys.Rev.B 62, 2797(2000).

Late submissions (21. March onward)

Dr. Andrew I Minett
Max-Planck-Insitute fuer Feskoerperforschung
Heisenberstr. 1

Stuttgart, D-70569
Germany
+49-711-689 1340 (phone)
+49-711-689 1010 (fax)
------------------------------------------------------------
Title: Towards the Development of a Single Nanotube Actuator - Manipulation of SWNT Properties Probed With An AFM
Authors: AI. Minett, J. Fraysse, S. Roth;
Affiliations: Max Planck Institute Fuer Feskoerperforschung, Heisenbergstr. 1, Stuttgart, D-70569, Germany
Abstract:
To demonstrate the viability of a single nanotube actuator, the growth, deposition and manipulation of suspended single walled carbon nanotubes has been the primary focus. To produce a single suspended SWNT a number of strategies have been attempted. These include the purification, disentanglement and deposition of tubes on substrates, the use of E-beam lithographic techniques, or the 'inverse' printing of tubes on pre-designed substrates. A second approach was the growth of tubes from metal catalyst patterned substrates. Characterisation of these structures was carried out by AFM, SEM and Raman. The final and most important step is the use of an atomic force microscope to manipulate and probe the mechanical properties of the suspended nanotubes. Operation of the AFM cantilever in a lateral mode using nanoscript commands was employed. Manipulation of tubes on substrates was first demonstrated before attempts were made to probe the suspended nanotubes. Measurements in both the dry state and also in an electrolyte solution during actuation have been attempted.
Dr. Henning Kanzow
GDPC, UMR 5581
Université Montpellier II
CC 026
Montpellier Cedex 05, 34095
France
+ 33/(0)467144778 (phone)
+ 33/(0)467522504 (fax)
------------------------------------------------------------
Title: Single-wall Carbon Nanotubes and Macroscopic Nanotube Fibers: Experiments and Theory
Authors: Henning Kanzow
Affiliations:
Abstract:
Vaporization of carbon metal mixtures in a plasma and the decomposition of carbon containing gases at metal nanoparticles are efficient production methods for single-wall carbon nanotubes. However, their formation mechanism is still debated. After comparing the different production methods, I will focus on two models based on a root growth mechanism. In the first model a thermodynamic equilibrium between the carbon in the gas phase and in the nanotubes is assumed. It predicts minimum tube diameters smaller than 0.5 nm. The second model concentrates on the transition state, in which precipitated graphene sheets detach from the surfaces of the catalyst particles forming fullerene like caps. The nanotube diameter distributions are calculated from energetic considerations depending on the formation temperature and the composition of the catalytic particle. The diameter distributions agree very well with the experimental data of arc and laser experiments. Finally a new product of the electric arc is presented, macroscopic fibers of nanotube bundles with diameters up to 0.5 mm and length up to 3 cm. SEM and TEM show that these fibers consist predominantly of single-wall carbon nanotubes and metal particles. X-ray diffraction measurements suggest a preferable orientation of the nanotubes along the fiber axis. RAMAN measurements will also be presented.
Dr. Zhongfang Chen
Institut fuer Organische Chemie
Universitaet fuer Erlangen-Nuerberg
Henkestr. 42
Erlangen, D-91054
Germany
(phone)
+49 9131 85 26864 (fax)
------------------------------------------------------------
Title: Endohedral chemical shifts in higher fullerenes with 72-86 carbon atoms
Authors: Zhongfang Chen,^{1,2} Jerzy Cioslowski, ^{ 3*} Niny Rao, ^{ 3} David Moncrieff, ^{3 } Michael B¨¹hl^{2}, Andreas Hirsch,^{1*} Walter Thiel ^{2*}
Affiliations: 1. Institut f¨¹r Organische Chemie, Universitaet Erlangen-N¨¹rnberg, 91054 Erlangen, Germany 2. Max-Planck-Institut fuer Kohlenforschung, 45466 Muelheim an der Ruhr, Germany 3. The Department of Chemistry and School of Computational Science and Information Technology, Florida State University, Tallahassee, Florida 32306-3006
Abstract:
For all isolated pentagon isomers of the fullerenes C_{60} - C_{86} with non-zero band gap and for one non-classical C_{72} isomer (C_{2v}), endohedral chemical shifts have been computed at the GIAO-SCF/3-21G level using B3LYP/6-31G* optimized structures. The experimental ^{3}He NMR signals are reproduced reasonably well in cases where assignments are unambiguous (e.g. C_{60}, C_{70} and C_{76}). On the basis of the calculated thermodynamic stability order and the comparison between the computed and experimental ^{3}He chemical shifts, the assignments of the observed ^{3}He NMR spectra are discussed for all higher fullerenes, and new assignments are proposed for one C_{82} and one C_{86} isomer (C_{82}:3 and C_{86}:17). The calculated helium chemical shifts also suggest the reassignment of the \{delta}(^{3}He) resonances of two C_{78} isomers.
Dr. Ofir E. Alon
Theoretical Chemistry, Physical Chemistry Institute, Heidelberg
Theoretical Chemistry, Physical Chemistry Institute
Im Neuenheimer Feld 229
Heidelberg, 69120
Germany
++49-6221-545264 (phone)
++49-6221-545221 (fax)
------------------------------------------------------------
Title: High Harmonic Generation of Soft X-Rays by Carbon Nanotubes
Authors: Ofir E. Alon, Vitali Averbukh and Nimrod Moiseyev
Affiliations: Department of Chemistry & Minerva Center for Non-Linear Physics of Complex Systems, Technion-Israel Institute of Technology, Haifa 32000, Israel
Abstract:
We extend the method for the formulation of selection rules for high harmonic generation spectra [Phys. Rev. Lett. {\bf 80}, 3743 (1998)] beyond the dipole approximation and apply it to single-walled carbon nanotubes interacting with a circularly polarized laser field. Our results show that the carbon nanotubes can be excellent systems for a selective generation of high harmonics, up to the soft x-ray regime.