ADSORPTION OF SB ON AG(111) STUDIED USING LEED, AES AND XPS

The growth of Sb overlayers on Ag(111) has been studied using LEED, AE S and XPS from sub-monolayer to multilayer coverages as a function of deposition temperature. At room temperature, growth was found to be by the Franck-van der Merwe (layer-by-layer) mechanism. Two distinct ord ered structures were seen after annealing of the deposited layers, a ( square-root 3 x square-root 3)R30-degrees at low coverage and a (2 squ are-root 3 x 2 square-root 3)R30-degrees at coverages above 1.5 monola yers. The first of these structures is thought to involve substituted Sb into the first layer of Ag atoms, forming a surface alloy. The seco nd structure may be due to the formation of an Sb overlayer on top of the Sb substituted layer. Small core level shifts were observed in the XPS spectra of the deposited surfaces.