G-band resonant Raman study of 62 isolated single-wall carbon nanotubes -: art. no. 155412

We report G-band resonance Raman spectra of single-wall carbon nanotubes (SWNTs) at the single-nanotube level. By measuring 62 different isolated SWNTs resonant with the incident laser, and having diameters d(t) ranging between 0.95 nm and 2.62 nm, we have conclusively determined the dependence of the two most intense G-band features on the nanotube structure. The higher-frequency peak is not diameter dependent (omega(G)(+)=1591 cm(-1)), while the lower-frequency peak is given by omega(G)(-)=omega(G)(+)-C/d(t)(2), with C being different for metallic and semiconducting SWNTs (C-M>C-S). The peak frequencies do not depend on nanotube chiral angle. The intensity ratio between the two most intense features is in the range 0.1