Charging shifts of core level peaks in X-ray photoelectron studies of argon-ion-bombarded carbon films on glass substrates☆

Abstract Carbon films grown by plasma-induced chemical transport in a nitrogen glow discharge and by spark evaporation of pyrolytic graphite were examined by X-ray photoelectron spectroscopy. Using argon ion bombardment for depth profiling, energy shifts of the C 1s and N 1s core level peaks are observed. Inherent partial recovery of the peaks towards their original energies occurs on leaving the ion-bombarded films in ultrahigh vacuum over a period of time. An interpretation of these energy shifts is given in terms of an initial induced dipole within the film. Rutherford backscattering was used to confirm argon atom implantation.