Adsorption-induced surface core-level shifts of Pt(110)

Abstract

A detailed investigation of surface- and adsorbate-induced binding-energy shifts of the Pt 4f core level has been carried out using photoemission with synchrotron radiation. Spectra recorded from the clean Pt(110)-(1×2) surface show a single surface peak shifted by -0.46 eV relative to the bulk peak. This result is discussed in light of recent structural studies of the reconstructed Pt(110) surface. Adsorption of H, atomic and molecular oxygen, and CO reveal two surface-atom contributions, whose origins are discussed. In some cases the second peak is believed to arise from former bulk atoms that are influenced by the adsorbate. The main adsorption-induced shifts correlate with thermodynamic data in the framework of a Born-Haber cycle. The shifts cannot be directly rationalized in terms of a charge transfer between the adsorbate and the Pt surface atoms.