Polarization effects to enhance surface sensitivity of angle- scanned X-ray photoelectron diffraction in synchrotron- radiation-based experiments

We show that the surface sensitivity of angle-scanned photoelectron diffraction applied to bulk crystals or epitaxial multilayers can be enhanced by exploiting the angular anisotropy of the photoelectron primary wave excited by linearly polarized light, combined with the possibility of performing measurements in two different light polarization/electron detection geometries. The obtained relative photoelectron diffraction patterns of the form I1(k)/I2(k), where 1 and 2 denote the two different geometric set-ups discussed in the present paper, show an enhanced structural surface sensitivity, which should allow the determination of the presence and the extent of surface relaxation by comparing the experimental data to suitable theoretical simulations. In a set of preliminary model calculations, the best results are obtained for emission from an s-initial state. High angular resolution of the electron detectors is an additional requirement.