Polarization-dependent C K near-edge X-ray absorption fine-structure of graphene

We report the polarization-dependent C K photoabsorption spectra of single-and few-layer graphene (FLG) samples produced by micromechanical cleavage of highly ordered pyrolytic graphite (HOPG) on a SiO(2) substrate. We show that the unoccupied sigma density of states of graphene and FLG strongly reflects the one measured on bulk HOPG, demonstrating the two-dimensional character of sigma states as well as the very-weak interlayer couplings between planes. Moreover, our spectra taken with different polarization allow us to show the predicted hybrid nature of the interlayer state. (C) 2009 Elsevier B. V. All rights reserved.