First and second-order resonance Raman process in graphite and single wall carbon nanotubes

Resonant Raman scattering for one single wall carbon nanotube spectroscopy is overviewed. First-order resonance Raman spectra of the radial breathing mode of one carbon nanotube is of importance for assigning (n, m) values to the nanotube. This assignment of (n, m) values is confirmed by the chirality dependence of other phonon modes. Second-order, one-phonon emission, and the inter-valley scattering processes of two dimensional graphite and of single wall carbon nanotubes are relevant to disorder-induced D-band Raman spectra. The dispersive nature of the D-band Raman spectra is explained by double resonance processes. Many weak Raman spectra appearing in the intermediate frequency range, which have been observed for a long time but never assigned so far, have recently been assigned as double resonance Raman peaks. The second-order Raman phonon frequencies can be used as a new fundamental tool for determining the phonon energy dispersion relations, especially for disordered materials and for zone boundary phonons.