Comparative second harmonic generation and X-ray photoelectron spectroscopy studies of the UV creation and O2 healing of Ti3+ defects on (110) rutile TiO2 surfaces

摘要: SHG studies on polished and etched (110) rutile TiO2 single-crystal surfaces suggest that above band gap, low-energy (4.7 eV) ultraviolet photons create stable Ti3+ surface defects in UHV. Such can be healed by subsequently exposing the to O2 gas. These results are similar recently reported measurements (001) surfaces. Observations were interpreted as photodesorption re-adsorption of molecular oxygen bound loosely a Ti4+:O−2 complex. For current study, XPS was used confirm defect type quantify density created. Defects studied using generated even lower energy (3.4 eV), indicating species removed very bound. The same creation healing processes also observed nearly defect-free thermally annealed XPS. Whether bridging ions or O−2 photo-labile has yet determined. Transient at high pressure SHG. proven sensitive probe defects, consistent with results, under conditions ranging from UHV atmospheric.