An XPS study on the surface reduction of V2O5(0 0 1) induced by Ar+ ion bombardment

The effect of the irradiation with Al Kα X-rays during an XPS measurement upon the surface vanadium oxidation state of a fresh in vacuum cleaved V2O5(0 0 1) crystal was examined. Afterwards, the surface reduction of the V2O5(0 0 1) surface under Ar+ bombardment was studied. The degree of reduction of the vanadium oxide was determined by means of a combined analysis of the O1s and V2p photoelectron lines. Asymmetric line shapes were needed to fit the V3+2p photolines, due to the metallic character of V2O3 at ambient temperature. Under Ar+ bombardment, the V2O5(0 0 1) crystal surface reduces rather fast towards the V2O3 stoichiometry, after which a much slower reduction of the vanadium oxide occurs.