AES study of electron beam induced damage on TiO2 surfaces

The damage induced by an electron beam on several TiO2 surfaces has been studied with Auger Electron Spectroscopy. We studied single crystal specimens of TiO2 (rutile) of the (100) and (110) orientation as well as pressed powder specimens consisting of rutile and a 65%–35% mixture of anatase and rutile. All surfaces acquired a (sometimes extremely high) negative charge upon electron irradiation. All surfaces did loose a significant amount of oxygen due to electron stimulated desorption. In the presence of background oxygen this process did not occur. Carbon (graphite) was deposited on the samples from residual gases. This is due to the decomposition of adsorbed carbonaceous species on the damaged surface and to the decomposition of positive gas phase ions on the negatively charged (irradiated) region of the surface. Significantly less carbon was deposited on the powder samples as compared to the single crystals. Carbon deposition is inhibited by the presence of oxygen in gas phase.