Oxygen KLL Auger spectra from O2 and CO adsorbed on Ni

High resolution oxygen KLL Auger spectra from O₂ and CO adsorbed on clean Ni (110) have been measured and compared. These Auger spectra are quite different from one another and are compared with spectra of the free molecules. Similarities between the oxygen spectra from adsorbed and gaseous CO are noted and interpreted as due to the weak bonding of CO to Ni with the O atom furthest from the surface. These Auger studies also characterize the change in bonding of adsorbed CO due to electron beam interaction.