Diameter dependence of the Raman D-band in isolated single-wall carbon nanotubes -: art. no. 041401

Raman D-band spectra are reported for several different SWNTs using two different laser energies (E-laser = 1.58 and 2.41 eV). At a fixed E-laser individual isolated SWNTs exhibit different diameter-dependent D-band frequencies omega (D) around an average value. For both semiconducting and metallic tubes, omega (D) decreases with decreasing nanotube diameter, though omega (D) for isolated metallic SWNTs is higher than for isolated semiconducting SWNTs. The average D-band frequency depends linearly on E-laser as previously observed for SWNT bundles, suggesting that the D-band in SWNTs is activated by defects or by the finite size of the SWNTs.