Coadsorption of Dioxygen and Carbon Monoxide on a Mg(100) Surface

The activation of carbon monoxide by oxygen on Mg(100) surface has been investigated by X-ray photoelectron spectroscopy (XPS). Carbon monoxide is only weakly adsorbed (dispersion-type forces) on a magnesium surface. The XPS result has shown that the dissociation of carbon monoxide leading to the formation of a metastable surface carbonate species occurs through the participation of an oxygen surface O¯(s). A stepwise mechanism involving a weakly adsorbed CO molecule present at very low surface coverage (<0.1) undergoing surface diffusion and interaction with the transient oxygen adatoms is suggested. The Frenkel equation has been used to estimate the mean residence time of CO molecule on the surface, and the residence time of a molecule on a specific surface site has also been estimated.