Anti-Stokes Raman spectra of single-walled carbon nanotubes

An analysis of the Stokes and anti-Stokes resonant Raman spectra of single-walled carbon nanotubes (SWNT's) using different laser energies in the range 1.49 less than or equal to E(laser)less than or equal to 2.19 eV shows major differences in the tangential band spectra for the Stokes and anti-Stokes processes for Selected E-laser values. These differences arise from the differences in the one-dimensional density of electronic states for metallic and semiconducting nanotubes. This observation allows selection of E-laser to excite only semiconducting or only metallic nanotubes in the Stokes and anti-Stokes spectra.