Probing the structure of single-walled carbon nanotubes by resonant Raman scattering

We review the main information that we have obtained from combined Raman spectroscopy and electron diffraction experiments on individual free-standing single-walled carbon nanotubes. This information concerns: the radial breathing mode vs. diameter relationship; the dependence of the frequency and lineshape of the G-modes in semiconducting and metallic tubes; the evaluation of the optical transition energies for individual free-standing SWNTs. From these data, we can define Raman criteria allowing the indexing of carbon nanotubes from their Raman features only. We show the efficiency of this approach to assign the (n,m) indices of individual chiral and achiral single-walled carbon nanotubes. These criteria are also applied to identify tubes grown on a substrate from a single wavelength Raman experiments. These results obtained on index-identified individual nanotubes are compared with theoretical predictions. (c) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim