Polarized photoluminescence excitation spectroscopy of single-walled carbon nanotubes.

The polarized photoluminescence excitation spectra of twenty-five single-walled carbon nanotube species are reported. For light polarized along the nanotube axis, the main absorption resonance at E22 shows sidebands attributed to phonon assisted absorption. Sidebands to E11 have a diameter dependent energy and are assigned to excited excitonic states. Along with longitudinal excitations, several transverse excitations are identified. The transverse E12 resonance has a specific family pattern with energy close to E22. Comparison with theory provides an estimate of the strength of the Coulomb interaction.