HREELS investigation of the coadsorption of CO and NO on Ni(111) at room temperature

Abstract

The adsorption of CO and NO, and the coadsorption of both species on Ni(111) at room temperature, has been studied by high resolution electron energy loss spectroscopy. Both CO and NO molecules adsorb without dissociation, giving the well-known c(4×2) LEED pattern. In the case of coadsorption, preadsorbed CO molecules are easily removed by incoming NO, whatever the initial CO coverage. In the reverse case, preadsorbed NO molecules inhibit CO adsorption for initial NO coverages higher than about 0.1 ML. For lower NO coverages, CO are allowed to adsorb, but their vibrational spectrum is substantially different from that observed for CO adsorption on the clean surface. The results are interpreted in terms of the different electronic structure of the two molecules.