COMPARATIVE SHG AND XPS STUDIES OF INTERACTIONS BETWEEN DEFECTS AND N2O ON RUTILE TIO2(110) SURFACES

In previous studies on TiO2(110) surfaces O-2 has been shown to heal T i3+ defects generated by above band-gap UV or low-energy electron-beam exposure. Electron affinity, rather than oxygen content may dictate w hether a molecule will interact with a defect to result in defect heal ing. This paper examines interactions between TiO2(110) surfaces and N 2O which has a substantial electron affinity. N2O is seen to heal defe cts at comparable exposures to those needed for O-2 healing. XPS indic ates that N2O heals defects by dissociating such that no nitrogen rema ins on the surface. XPS could detect no difference between surfaces he aled by N2O and those healed by O-2. However, SHG indicates that surfa ces healed by N2O differ slightly from surfaces similarly healed by O- 2, suggesting that O-2 may interact with defects on these surfaces to form Ti4+:O-2(-) complexes. (C) 1997 Elsevier Science B.V.