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 radiation, and ab initio self-consistent-field calculations. The formation of S-Pt(111) bonds leads to a large decrease in the density of 5d states that the metal atoms exhibit around the Fermi level of the surface. 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 interactions. These states desorb from the surface following distinct reaction pathways.