Diameter grouping in bulk samples of single-walled carbon nanotubes from optical absorption spectroscopy

The influence of the synthesis parameters on the mean characteristics of si ngle-wall carbon nanotubes in soot produced by the laser vaporization of gr aphite has been analyzed using optical absorption spectroscopy. The abundan ce and mean diameter of the nanotubes were found to be most influenced by t he furnace temperature and the cobalt/nickel catalyst mixing ratio. Via an analysis of the fine structure in the optical spectra, the existence of pre ferred nanotube diameters has been established and their related fractional abundance could be determined. The results are consistent with nanotubes l ocated mainly around the armchair axis. (C) 1999 American Institute of Phys ics. [S0003-6951(99)04241-2].