The defective nature of the TiO2(110) (1×2) surface

(1×1) and the (1×2) reconstructed TiO2(110) surfaces have been studied with photoelectron spectroscopy of the valence bands and of the Ti 3p core level using synchrotron radiation. There is a higher defect concentration within the sample upon transformation of (1×1) to (1×2). The defects with both surfaces are isolated and are not limited to the surface. Defects induced by exposure to low-energy electrons at room temperature are mainly located at the topmost surface layer as a result of electron stimulated desorption. Electron beam irradiation, while destroying long-range order, yields a significant overlap between defect states and promotes the formation of band-gap states tailing towards the valence band.