Abstract
Metal/oxide chemistry and metal cluster growth on oxides are fundamental to our understanding of the catalytic activity and selectivity of metal catalysts, thus considerable research recently has addressed the physical and chemical properties of metal clusters on well-defined oxide surfaces. In this work, the nucleation and growth modes of Ag on TiO₃(110)(1x1) and (1x2) surfaces, Ag on ultra-thin Al₂O₃ films, and Au on ultra-thin SiO₂ films were studied by scanning tunneling microscopy (STM), low energy ion scattering spectroscopy (LEIS) and X-ray photoelectron spectroscopy (XPS). In general, Ag grows three-dimensionally (3D) on both TiO₂(110) and Al₂O₃ film at 300 K. The growth mode of Au at fractional monolayer coverages is quasi-two dimensional (2D); at higher coverages, three-dimensional growth of Au was found. In these three systems, Ag/TiO₂, Ag/Al₂O₃, and Au/SiO₂, no strong chemical interaction was observed between metal clusters and substrates. Sintering was observed for all metal clusters upon annealing. A non-zero order desorption was observed for Ag/Al₂O₃ and Au/SiO₂ in temperature programmed desorption (TPD) studies. The desorption activation energies decrease with decreasing metal coverages.
Luo, Kai (2000). Spectroscopic studies of metal growth on oxides. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2000 -THESIS -L834.