Temperature dependence of the x-ray photoelectron spectrum of molybdenum bombarded with hydrogen ions

Abstract

The surface chemistry determined by X-ray photoelectron spectroscopy (XPS) for molybdenum under hydrogen ions bombardment at different temperatures is described. A marked temperature dependence was found in the chemical state of Mo bombarded with hydrogen ions. At around 473 K the XPS showed a marked change in surface chemical state mainly due to oxidization under the hydrogen bombardment. On the other hand, the Auger electron analyses showed that the average oxygen concentration decreases monotononically with temperature. This anomalous chemical behavior was not observed in the case of only heating in a hydrogen gas at the same temperature. These results show the occurrence of a hydrogen ion-bombardment induced reaction on the surface at around 473 K. This may attributed to the activation of molybdenum surface during the hydrogen ion bombardment, which should accelerate the chemical absorption reaction of the surface with the impurities. It was suggested from the XPS spectra that a hydrogen bronze-like compound may be formed on molybdenum surface by the hydrogen ion bombardment.