An X-ray absorption and photoelectron diffraction study of the Cu{100} c(2 × 2) CO structure

Abstract

The structure of CO adsorbed on Cu{100} has been investigated using near edge X-ray absorption fine structure at the oxygen K-edge to determine the molecular orientation, and normal emission photoelectron energy-intensity spectra for the C 1s and O 1s core levels to determine the adsorption site. The photoelectron diffraction data have been interpreted by comparison with the results of single scattering model calculations. Good agreement is found for CO molecules adsorbed normal to the surface on on-top sites with a CuC distance of 1.92±0.05 A ̊ , in accordance with a previous LEED study. Calculations show that intramolecular scattering can be rather unimportant for this technique and that the individual atomic sites may then be obtained from the photoelectron diffraction spectrum by studying the emission from the relevant atom and scattering from the substrate. The method should therefore be applicable to more complex molecular adsorbates.