PHOTOEMISSION-STUDY OF THE ELECTRONIC-STRUCTURE OF SIZE-SELECTED PTN- CLUSTERS DEPOSITED ON AG(110)

We report on a photoemission study (XPS, UPS) of the evolution of the electronic structure with cluster size of Ptn(n=1-10) clusters deposited on a Ag(110) single crystal surface. The clusters are produced by Xe-ion bombardment of a Pt target. The ionized clusters are mass-selected by a quadrupole mass spectrometer and guided to the substrate by an RF-mode only quadrupole. The substrate is in the center of the analysis chamber allowing in-situ characterization of the supported clusters. Photoemission spectra taken on submonolayer quantities of mass-selected monodispersed Pt clusters indicate individual discrete electronic structure features of the Pt 5d emission. In the atomic-like limit virtual bound state formation with different 5d3/2 and 5d5/2 line broadening is observed which points to an energy dependent V(sd) hopping matrix element in agreement with theoretical predictions. With increasing cluster size the splitting between the bonding-like and antibonding-like Pt 5d states reflects the Pt-Pt interaction. The shift of the center of gravity of the Pt 5d state towards the Fermi energy and their concomittant broadening indicate the trend to Pt-metal formation.