SPECTROSCOPIC ANALYSIS OF DIFFERENT TYPES OF SINGLE-WALL CARBON NANOTUBES

The Raman response of the radial breathing mode in single-wall carbon nanotubes was analyzed for excitation with 10 different laser lines. T he line shape was fitted with 14 Voigtian oscillators which could be c orrelated to tubes of different helicity. The strongest lines were obs erved between 172 and 199 cm(-1). For an assignment frequencies evalua ted from a density functional calculation and scattering intensities f or the resonance transitions were used. The 5 strongest lines observed are consistent with scattering from tubes with 11 different helicitie s. From the evaluation of the scattering intensities the nearest-neigh bor integral between two carbon atoms on the curved sheet was found to be 2.6 +/- 0.5 eV.