Diameter dependence of the Raman (formula presented)-band in isolated single-wall carbon nanotubes

Abstract

Raman D-band spectra are reported for several different SWNTs using two different laser energies (formula presented) and 2.41 eV). At a fixed (formula presented) individual isolated SWNTs exhibit different diameter-dependent D-band frequencies (formula presented) around an average value. For both semiconducting and metallic tubes, (formula presented) decreases with decreasing nanotube diameter, though (formula presented) for isolated metallic SWNTs is higher than for isolated semiconducting SWNTs. The average D-band frequency depends linearly on (formula presented) 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. © 2001 The American Physical Society.