Raman characterization of electronic transition energies of metallic single-wall carbon nanotubes

Using a confocal micro-Raman system, spectra showing the splitting of optical transitions due to trigonal warping effect are presented for metallic single-wall carbon nanotubes (SWNT's). Our results indicate that the intensity variations between different optical transitions can be attributed primarily to the differences in the magnitude of the electron-phonon coupling matrix elements. Our approach will allow the study of the magnitude of electron-phonon matrix elements as well as quantum interference effects between different transitions in metallic SWNT's.