Carbon 1s X-ray photoemission line shape analysis of highly oriented pyrolytic graphite: The influence of structural damage on peak asymmetry

C 1s XPS spectra of various highly oriented pyrolytic graphite (HOPG) surfaces, untreated, as well as those treated by keV Ar+ beam bombardment and low-energy O-2, N-2, Ar, and H2O plasmas, have been systematically studied by comparing two XPS peak-fitting procedures. These procedures treat the spectrum as either (1) the overlap of several symmetric component peaks or (2) a single asymmetric peak. The results indicate that, in the case of HOPG, the asymmetry parameter defining the single peak is directly related to the extent of damage to the alternant hydrocarbon structure of the HOPG surface, as manifested by its correlation with the symmetric peak component due to the damaged HOPG structure.