A multiple-scattering approach to X-ray photoelectron diffraction

We present an alternative method for multiple scattering calculations of X-ray photoelectron diffraction from periodic surfaces. The technique uses a time-reversed RHEED wave function as the final state in a one-step model of the photoemission process. We apply the method to the Ni(001)c(2×2)S system and find an excellent agreement with the experimental data for vertical height of the S overlayer of 1.35±0.05 Å above the top Ni layer. Our calculations display a much better agreement with the experimental data than has been previously reported.