The structure of ordered Au films on TiOx

The growth of Au on an ultra-thin, ordered Mo(1 1 2)–(8 × 2)-TiOx, was investigated using scanning tunneling microscopy (STM), low energy ion scattering spectroscopy (LEISS), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption (TPD). Wetting of the TiOx surface by Au was observed with STM and LEISS, and the ordering of the Au films was atomically resolved with STM. TPD showed that Au binds more strongly to the reduced TiOx film than to bulk TiO2, but more weakly than to the Mo substrate. The Au–TiOx binding energy is greater than Au–Au in bulk Au. The oxidation state of Ti in the TiOx film was deduced by XPS and from the Ti–O phonon shifts relative to bulk TiO2. The TiOx/Mo(1 1 2) film structure and those for the (1 × 1)- and (1 × 3)-Au/TiOx/Mo(1 1 2) surfaces are discussed.