Abstract Submitted to the    NANOTUBE'04 Conference:

This work reports observation of selective Resonance Raman scattering of the intermediate frequency modesin carbon nanotubes. The experimental work (Raman spectra with 22 different excitation energies into a 0.8,eV energy range) allowed us to construct a 2D Raman spectra, by plotting the Raman shift in the abscissa and the laser energy in the ordinate. This work reports a new and very unusual phenomenon in Raman spectroscopy, with important new information on the electron-phonon interaction and on acoustic-like waves in a 1D system. Although restrictions on the electron-phonon interaction are not severe in conventional 3D solids, they appear to be strongly selective in single wall carbon nanotubes, due to the presence of van Hove singularities in both the electron and phonon density of states, resulting in a turn-on/turn-off effect for the scattering process. Selection of very special SWNTs, that is those in the family mod(2n+m,3)=1 and with low chiral angle, is shown to be due to quantum confinement of electrons and phonons bounded by symmetry selection rules.