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Graphene, a single layer of carbon atoms arranged in a honeycomb lattice, is the building block of C60, nanotubes, graphite, and other mesoscopic carbon systems. As such, graphene is a model system whose properties should be studied in order to understand exotic phenomena in similar carbon-related systems. It is also interesting in its own right since graphene has the potential to play an important role in future electronic technologies, and may display its own interesting fundamental 2-dimensional phenomena reflected in transport measurements. The recent isolation of high-quality, few-layer graphene by exfoliation and by epitaxial growth has led to an explosion of theoretical and experimental studies of graphene. The carrier dynamics in graphene can be explored directly using angle-resolved photoemission spectroscopy (ARPES), which determines the lifetime and mass renormalization of the carriers. In the talk we will present ARPES measurements of single layer graphene films grown on SiC substrates, the evolution of the 3D band structure upon growth of films of several monolayer thickness, a gap opening and closing in bilayer graphene as a function of doping, and the influence of many-body effects on the band structure of graphene. The bands are fitted to a tight-binding (TB) model, which simulates the bands very well except in the vicinity of the Dirac and Fermi levels (ED and EF), where the bands are renormalized by many-body interactions, namely electron-plasmon, electron-electron, and electron-phonon interaction. These renormalizations turn out to be enhanced by increasing carrier concentration, which we determined by measuring the bands as a function of n-doping by alkali metal adsorption. |