Department of Chemistry

Tuesday, March 27, 2012 - 11:00am
Chemistry, Room 400

 We explore the fundamental nature and dynamics of excited electronic states in graphitic carbon materials.  In semiconducting carbon nanotubes, near-infrared two photon luminescence excitation spectra quantitatively reveal very-strongly-bound exciton excited states.  Electron-electron interactions are compared among CdSe nanocrystals, graphene, and carbon nanotubes.  The independent contributions of screening and dimensionality to increased electron correlation in nanostructures are analyzed.  Electronic and vibrational degrees of freedom are significantly coupled in graphene.  The metallic versus molecular nature of single sheet graphene is strongly affected by charge transfer doping by adsorbed molecular species.   Asymmetric doping in bilayer graphene can open a band gap, as revealed by the Raman spectra. Few layer graphenes very highly doped by adsorbed alkalis show optical absorption bleaching and Fano Raman line shapes.