Raman characterization of single wall carbon nanotubes prepared by the solar energy route

A Raman scattering characterization is reported that confirms the preparati on of single wall carbon nanotubes (SWNT) by the solar energy route. The re sults are presented for samples synthesized with various catalysts-mixtures of Ni and Co (Y, La)-and compared to those obtained from electric are disc harge or laser ablation. In the light of the calculations of the vibrationa l spectra of SWNT by Eklund et al. (Carbon, 1995, 33, 959) it is shown that both the diameter and structure of the nanotubes depend strongly on the sy nthesis conditions. For the First time the presence of nanotubes with "zigz ag" or "chiral" helical pitches for some of the samples are shown as well a s a large distribution of tube diameters. (C) 1998 Elsevier Science Ltd. Al l rights reserved.