Raman scattering study of electrochemically doped single wall nanotubes

Sheets of single wall carbon nanotubes (SWNT) bundles were studied by Raman scattering spectroscopy when doped electrochemically in an aqueous NaCl solution. At non-resonant conditions, the radial breathing mode (RBM) and tangential displacement modes (TDM) change very little intensity and frequency with electrochemical doping. Resonant Raman scattering for the TDM band, however, show large changes when applying or negative voltages. We conclude that the electronic resonance condition disappears due to larger change of the electronic occupancy with electrochemical doping.