Co adsorption on Ru(101̄0) modified with different amounts of Cu

Abstract

The adsorption of CO at 300 K on Ru(101̄0) modified with different amounts of Cu has been studied using Auger electron spectroscopy (AES), thermal desorption (TD), electron energy loss spectroscopy (EELS), LEED and work function (WF) measurements. It was found that the effect of the coadsorbed Cu on the CO adsorption kinetics and energetics depends strongly on the actual Cu surface site occupation and coverage, θ Cu . The presence of Cu up to θ Cu = 1 ML was found to cause no changes in the CO initial sticking coefficient, S 0, and initial dipole moment, but reduces the CO saturation coverage. At θ Cu > 1 ML, both the CO initial sticking coefficient and the initial dipole moment are reduced, accompanied with a complete removal of the CO adsorption states at 300 K, starting with the most tightly bound one. The observed behavior of CO on Cu/Ru(101̄0) was discussed in the framework of the precursor state model for CO adsorption and ensemble and ligand effects on modified surfaces.