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 $1.49<~E_{\mathrm{laser}}<~2.19$ eV shows major differences in the tangential band spectra for the Stokes and anti-Stokes processes for selected $E_{\mathrm{laser}}$ 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 $E_{\mathrm{laser}}$ to excite only semiconducting or only metallic nanotubes in the Stokes and anti-Stokes spectra.

• Received 25 August 1999

DOI:https://doi.org/10.1103/PhysRevB.61.R5137