Some aspects of an AES and XPS study of the adsorption of O2 on Ni

Some aspects of the adsorption of O2 on Ni have been studied using electron‐excited Auger electron spectroscopy (AES) and x‐ray photoelectron spectroscopy (XPS). Changes in the oxygen Auger line shape were observed with increasing oxygen exposure, together with a broadening and energy shift of the main oxygen Auger peak. Measurements were also made of the broadening and energy shifts of the Ni L3VV Auger peak on oxidation. The variation in oxygen Auger signal strength with oxygen exposure shows that two distinct adsorption stages occur. Relative AES and XPS signal strengths from clean and heavily oxidized Ni were measured and compared with the atomic densities of Ni in pure Ni and NiO. To accurately measure the changes in signal strengths, the AES and XPS data had to be integrated to remove the effects of line shape changes.