Initial growth and oxygen adsorption of silver on Al2O3 film

The growth and oxygen adsorption of Ag on an ordered Al2O3 film, prepared on Mo(110) substrate, have been studied in situ under ultrahigh-vacuum condition using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and low-energy electron diffraction. The results show that Ag particles/clusters are formed on alumina film at initial coverages, and the binding energy of the Ag 3d(5/2) line for Ag clusters is higher than that of bulk Ag, arisen from the size effect. Exposure of Ag clusters to similar to 10(-7) mbar O-2 leads the clusters to spreading over the substrate. It is of importance in many application areas to understand the origin of oxygen-induced metal-cluster changes in morphology and size.