Optical Transition Energies for Carbon Nanotubes from Resonant Raman Spectroscopy: Environment and Temperature Effects

This Letter reports the laser energy dependence of the Stokes and anti-Stokes Raman spectra of carbon nanotubes dispersed in aqueous solution and within solid bundles, in the energy range 1.52--2.71 eV. The electronic transition energies (${E}_{ii}$) and the radial breathing mode frequencies (${\ensuremath{\omega}}_{\mathrm{R}\mathrm{B}\mathrm{M}}$) are obtained for 46 different (18 metallic and 28 semiconducting) nanotubes, and the $(n,m)$ assignment is discussed based on the observation of geometrical patterns for ${E}_{ii}$ versus ${\ensuremath{\omega}}_{\mathrm{R}\mathrm{B}\mathrm{M}}$ graphs. Only the low energy component of the ${E}_{11}^{M}$ value is observed from each metallic nanotube. For a given…