Vibrational spectra of single wall carbon nanotubes

Raman and infrared spectra have been measured for singlewall nanotubes grown by the laser evaporation method. The Raman spectra were recorded with six different laser energies which allowed a detailed analysis of the photoselective resonance scattering. Recording and analysis is concentrated on the radial breathing mode. Three different types of tubes were found, each of them with a narrow distribution of diameters. From a comparison with calculations by Jishi et ai. two of the observed types were assigned to the armchair tubes and to the zigzag tubes, respectively. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.