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<~Eₗₐₛₑᵣ<~2.19 eV shows major differences in the tangential band spectra for the Stokes and anti-Stokes processes for selected Eₗₐₛₑᵣ 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 Eₗₐₛₑᵣ to excite only semiconducting or only metallic nanotubes in the Stokes and anti-Stokes spectra.