Determination of Local Atomic Arrangements at Surfaces from Near-Edge X-Ray-Absorption Fine-Structure Studies: O on Ni(100)

Abstract

Near-edge x-ray-absorption fine-structure (NEXAFS) spectra for oxygen adsorption on Ni(100) are found to exhibit pronounced variations with oxygen exposure and x-ray incidence angle. The measured spectra are compared to calculations of the NEXAFS with use of a multiple-scattering formalism. The theory shows considerable sensitivity to changes in the O-Ni coordination and x-ray incidence angle. By comparison of experimental and theoretical spectra NEXAFS is shown to be a new technique for determining the local structure of adsorbates on surfaces.