Stimulated desorption studies of defect structures on TiO2

The influence of the surface geometric structure on the electron and photon-stimulated desorption (ESD, PSD) ion yield from TiO₂(001) and TiO₂(110) has been studied. For both surfaces, angle-integrated ESD yields have been measured as a function of annealing temperature ranging from room temperature sputtered surfaces to 1200 K annealed surfaces. These measurements imply that the local geometry of the desorption site must be considered in order to adequately explain the observed ion yield variations. The ESD ion angular distribution (ESDIAD) patterns have been obtained after annealing in the temperature range 300–1200 K. These patterns show the presence of short-range structural order, even on highly defective, sputtered surfaces, and they are interpreted in terms of plausible models of surface structure. Changes in both the surface Ti-cation valence state and its coordination number as a function of annealing temperature are proposed to give rise to the observed ESDIAD patterns and the total ion yield behavior.