Abstract Submitted to the NANOTUBE'02 Workshop:

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. Sonication of single walled carbon nanotubes in sodium dodecylsulfate (SDS) water solution followed by centrifugation was used to remove tube bundles, ropes, and residual catalyst, leaving individual nanotubes each encased in a cylindrical micelle. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes, and substantially broadens the absorption spectra. At pH < 5 the absorption and emission spectra of individual nanotubes show evidence of band-gap-selective protonation of the tube side wall. This protonation is readily reversed by treatment with base or ultraviolet light.