XPS and UPS studies on electronic structure of Li2O

The adsorption behavior of H2O on Li2O was studied by X-ray photo electron spectroscopy (XPS) and ultraviolet photo electron spectroscopy (UPS). XPS and UPS spectra of Li2O single crystals which were exposed to different pressure of H2O vapor were observed. In O(1s) region, two peaks were observed and they were assigned to O(1s) in precipitated LiOH on the surface and O(1s) in Li2O. After H2O exposure, a peak broadening and an appearance of a new peak were observed at the higher binding energy region than O(1s) in Li2O. They were attributed to surface −OH and H2O molecule adsorbed on the surface. The adsorption behavior of H2O was discussed from the observation of electronic structure in Li2O surface.