For the second seminar of the Fall 2011 semester to be held on Thursday, September 22, 2011, we are pleased to welcome Professor Apparao M. Rao from the Department of Physics and Astronomy at Clemson University.  His talk is titled "Optical Properties of CVD-grown Graphene"

Abstract:
A single sheet of sp2- hybridized carbon atoms, called graphene, is presently the most widely studied material in the scientific community. Following a brief introduction of graphene and its unique properties, I will present two popular methods for preparing graphene for spectroscopic studies. In carbon science, spectroscopy has played a significant role in unraveling several fundamental properties of nanostructured carbons like fullerenes and carbon nanotubes. Drawing from such spectroscopic studies, the effective roles of Raman and UV-vis spectroscopy in elucidating the the vibration and electronic properties of graphene will be discussed. Specifically, the effects of crystallite size (La) on the linear and non-linear optical properties of chemical vapor deposition grown polycrystalline graphene will be presented.  In comparison to epitaxial graphene layers grown on SiC wafers which ehibit a photogenerated carrier lifetime of few picoseconds, we find that the photogenerated carriers in our CVD-grown graphene can exhibit lifetimes as long as nanoseconds. Time permitting, preliminary data on doped graphene will also be discussed.