Auger Electron Spectrum and Electron Energy Loss Spectrum of Oxygen Adsorbed CaF2(111) Surface

A highly insulating CaF 2 surface was investigated by Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS). Reduction of primary electron current could suppress the surface deterioration during electron spectroscopy, which enabled the AES measurement of a stoichiometric CaF 2 surface for the first time. Combination of AES and EELS proved useful for understanding of a CaF 2 surface and was applied to the study on the mechanism of oxygen adsorption on electron bombarded CaF 2 surfaces. It has been found that oxygen substitutes the fluorine vacant site for the lightly damaged surface, while reaction with oxygen proceeds for the heavily damaged surface.