PHOTOEMISSION-STUDIES OF PD AND PT IMPURITIES ON AND IN SILVER

The electronic structure of Pd and Pt atoms adsorbed on the (100), (11 0), and (111) surfaces of silver and of the related dilute alloys has been studied at different temperatures using ultraviolet photoelectron spectroscopy (UPS). The observed differences in lineshape of the virt ual bound palladium 4d (platinum 5d) state on isolated atoms supported on the differently oriented surfaces in comparison with an impurity a tom embedded in the first layer and in the bulk are well accounted for by a many-body calculation performed within the Anderson single impur ity model. This analysis clearly indicates a stronger sd-hybridization in the bulk than at the surface, consistent with the change in coordi nation number.