THE BONDING OF SULFUR TO A PT(111) SURFACE - PHOTOEMISSION AND MOLECULAR-ORBITAL STUDIES

The electronic properties of S/Pt(111) surfaces have been investigated using high-resolution photoemission spectroscopy with synchrotron rad iation, and ab initio self-consistent-field calculations. The formatio n of S-Pt(111) bonds leads to a large decrease in the density of 5d st ates that the metal atoms exhibit around the Fermi level of the surfac e. This reduces the chemical reactivity of Pt. On Pt(111), S is bonded to two dissimilar adsorption sites (hollow and probably bridge) that show well separated S 2p binding energies and different bonding intera ctions. These states desorb from the surface following distinct reacti on pathways.