|
|
Seminar AbstractOptical Properties of Carbon Nanotubes and Single Sheet GrapheneColumbia University Tuesday, November 3rd 1:25 PM
We explore the fundamental nature and dynamics of excited electronic states in single wall carbon nanotubes (SWNT). Near infrared two photon luminescence excitation spectra quantitatively reveal strongly bound exciton excited states in semiconducting tubes. Electron-electron interactions are very strong. In order to characterize metallic and semiconducting individual tubes, we observe both resonant Rayleigh and Raman scattering. In single sheet graphene, the Fermi level, and metallic versus molecular character, is strongly affected by environmental chemical doping. This is revealed by the Raman spectrum. Two layer graphene can develop a band gap in the presence of a perpendicular electronic field. We observe that a band gap can also open in three layer and thicker graphenes, due to surface doping by adsorbed species. |
|
