Angle-resolved XPS investigations of the interaction between O 2 and Mo 2C/Mo(1 0 0)

Abstract

The interaction of oxygen with a carbidized Mo(1 0 0) surface was investigated at different temperatures (300 K–1000 K) with-angle resolved X-ray photoelectron spectroscopy. A carbide overlayer with a homogeneous Mo 2C stoichiometry (down to the information depth of XPS) was produced by the high-temperature decomposition of C 2H 4 on Mo(1 0 0). O 2 adsorbs dissociatively on Mo 2C/Mo(1 0 0) at room temperature. Oxidation of the carbide at 800 K results in the partial removal of carbon and leads to sub-surface O migration, accompanied by the appearance of highly oxidized Mo states. Raising the O 2 adsorption temperature to 900 K decreased the carbon content further, without affecting the amount and the distribution of adsorbed O. Performing the oxidation at 1000 K led to an even more effective removal of carbon, but the oxygen content of the surface region was also reduced.