AES STUDY OF ELECTRON-BEAM-INDUCED DAMAGE ON TIO2 SURFACES

The damage induced by an electron beam on several TiO2 surfaces has be en 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% mixtur e of anatase and rutile. All surfaces acquired a (sometimes extremely high) negative charge upon electron irradiation. All surfaces did loos e a significant amount of oxygen due to electron stimulated desorption . In the presence of background oxygen this process did not occur. Car bon (graphite) was deposited on the samples from residual gases. This is due to the decomposition of adsorbed carbonaceous species on the da maged surface and to the decomposition of positive gas phase ions on t he negatively charged (irradiated) region of the surface. Significantl y less carbon was deposited on the powder samples as compared to the s ingle crystals. Carbon deposition is inhibited by the presence of oxyg en in gas phase.