OXIDATION STUDIES OF THE GRAPHITE SURFACE BY SCANNING-TUNNELING-MICROSCOPY AND PHOTOELECTRON-SPECTROSCOPY

Scanning tunneling microscopy and spectroscopy and X-ray photoelectron spectroscopy were used to study oxidation effects of nitric acid on h ighly oriented pyrolytic graphite surface. This treatment was performe d at different temperatures and etching times with the aim of realizin g local binding sites on the surface without creating deep defects. Th en these three technics were found in good agreement to characterize t he weakly oxidized surface. A wavy structure different from pure graph ite at atomic scale was imaged by scanning tunneling microscopy. This modification was correlated to the presence of carboxylic groups on th e surface revealed by X-ray photoelectron spectroscopy. Both spectrosc opies of scanning tunneling and X-ray photoelectron demonstrated the v anishing of pi bands characteristic from sp2 graphitic hybridization. This was attributed to dehybridization corresponding to new bondings o f the graphite carbons in the carboxylic groups.