Two ( 1×2) Reconstructions of TiO ₂(110): Surface Rearrangement and Reactivity Studied Using Elevated Temperature Scanning Tunneling Microscopy

We have employed elevated temperature scanning tunneling microscopy to elucidate the reactivity and surface structure of the (1×2) reconstructed TiO ₂(110) surface. We find two distinctly different ordered surface reconstructions 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 Ti ₂O ₃ type termination. For heavily reduced crystals a cross-linked (1×2) reconstruction forms with high activity to oxygen resulting in a well-defined cyclic reaction ( TiO ₂ growth).