A thermal desorption study of the adsorption of CO on Fe(110); enhancement of dissociation by surface defects

Abstract

The adsorption and desorption kinetics of CO on Fe(110) was studied by Thermal Desorption Spectroscopy. Our results indicate that the adsorption takes place via a mobile weakly bound precursor state that also influences the desorption kinetics as concluded by analysing the desorption spectra. We have also investigated the role of surface defects produced by argon sputtering on the rate of dissociation of carbon monoxide and we have found that, on a slightly sputtered surface 36% of the adsorbed CO molecules will undergo dissociation, whereas on an annealed surface only 20% of the adsorbed CO molecules will dissociate. This seems to suggest that surface defects act as active sites for carbon monoxide dissociation on Fe(110) probably through a decrease in the activation barrier for dissociative chemisorption.