Oxygen chemisorption on Cr(110): II. Evidence for molecular O 2(ads)

Abstract

Oxygen chemisorption and dissociation on Cr(110) at 120 K have been studied using high resolution electron energy loss spectroscopy (HREELS), electron stimulated desorption ion angular distribution (ESDIAD), low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). Dissociative adsorption dominates although vibrational and stimulated desorption data provide evidence for a coexisting minority molecular binding state. An O 2(ads) vibrational frequency of 1020 cm −1 and a six beam ESDIAD pattern are suggestive of super-oxo O 2(ads) bonding at six local sites each with the O-O molecular axis tilted away from the surface normal. These results are compared with data for chemisorbed oxygen on other transition metal surfaces.