Non-dipole photoemission effects in x-ray standing wavefield determination of surface structure

Non-dipolar effects in the angular distribution of core level photoemission are shown to have a substantial influence on the interpretation of x-ray standing wavefield determinations of surface adsorption structures when the x-ray absorption is monitored by photoemission, even at photon energies below 3 keV. Results for I adsorption on Cu(111) are shown to be compatible with theoretical calculations for atomic Xe.