Raman spectroscopy study of Ar+ bombardment in highly oriented pyrolytic graphite

In this work, we discuss the effect of low energy Ar+ ion bombardment on highly oriented pyrolytic graphite (HOPG). The evolution of the G and D peak intensities are analyzed as a function of ion dose, as well as the evolution of a broad densityof-states (DOS)-like background. For low ion doses, a small D band is observed. It increases and finally gives place to the broad DOS-like feature. The I-D/I-G, analysis clearly shows three distinct regimes. No frequency shifts are observed, indicating sp(2) bondings are mostly preserved. Comparison between preliminary work on single-layer graphene and HOPG shows the effect observed in HOPG is limited to the top surface. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim