Abstract Submitted to the    NANOTUBE'04 Conference:

Following a recent debate about the resonance nature of the tangential (G) band in the Raman spectra of single-wall carbon nanotubes (SWNT) we measured the Raman spectra of isolated and bundled (aligned and misaligned) SWNT samples, with different excitation laser energies (Elaser). This study shows that the G band can be originated from both single and double resonance mechanisms. By performing Raman spectroscopy using different Elaser, we can separate the contribution from single and double resonance processes. The G band has a single resonance scattering nature with a strong intensity in non-defective nanotubes. These G band spectra present a non-disperse behavior and keep the selection rules of the first-order Raman scattering. However, in defectives samples, the G band spectra is two orders of magnitude lower than the spectra in non-defective sample, and it is composed both by single resonance and dispersive defect-induced double resonance processes.