Oxidation of Mg(0001): A combined Experimental and Theoretical Study

Other conference contribution, 2002

The oxidation of magnesium proceeds in several stages, beginning with the oxygen dissociation process and ending with the formation of magnesium oxides. Our focus is on the intermediate oxidation state at the Mg(0001) surface, whose geometrical structure is an unsettled problem. By combining the results of high-accuracy electronic structure calculations with angle-scanned x-ray photoelectron diffraction measurements we are able to unambiguously determine the structure of the Mg(0001) surface upon oxidation. In contrast to previous studies of Mg(0001) oxidation and unlike the case of aluminum oxidation we find a rather unanticipated surface oxide structure, consisting of two mixed oxygen-magnesium layers on top of an almost undisturbed Mg(0001) surface. This unusual surface oxide structure is locally formed already at very low coverages of 0.1 monolayer and grows laterally with increasing oxygen coverage up to 2 monolayers.