Two (1 x 2) reconstructions of TiO2(110): Surface rearrangement and reactivity studied using elevated temperature scanning tunneling microscopy

We have employed elevated temperature scanning tunneling microscopy to eluc idate the reactivity and surface structure of the (1 x 2) reconstructed TiO 2(110) surface. We find two distinctly different ordered surface reconstruc tions depending upon the level of bulk reduction of the crystal (degree of nonstoichiometry). On the near stoichiometric surface reactivity to oxygen is low and attributed to the formation of the stable Ti2O3 type termination . For heavily reduced crystals a cross-linked (1 x 2) reconstruction forms with high activity to oxygen resulting in a well-defined cyclic reaction (T iO2 growth).