Discussion Topic Posted for the NANOTUBE-99 Workshop:

There appears to be no definitive agreement regarding the real topology of multi-wall nanotubes which have been discovered by Sumio Iijima, who was observing in a TEM the structure of the cathode of the carbon arc that had been used to produce fullerenes [1]. The projected images can not easily be used to distinguish between nested, independent cylinders and a "scroll".

• One of the strongest arguments in favor of independent graphitic cylinders is the abundance of cylindrical multi-wall structures in an aggressive atmosphere. A scroll, with an exposed edge along the entire tube axis, should be rapidly etched away under synthesis conditions, unlike a set of independent cylinders that are exposed only at their ends.
• The scroll model would provide a natural explanation of the fact that the inner diameter of multi-wall tubes is in most cases significantly larger than that of single-wall tubes.

[1] S. Iijima, "Helical microtubules of graphitic carbon", Nature 354, 56 (1991).

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