An analysis of angular dependent XPS peak intensities

Angle resolved X-ray photoelectron (XPS) studies of clean Ni(100) and of exitaxial Cu and Co films on Ni(100) have been interpreted with the aid of single scattering cluster calculations. It is found that for atoms in the top few atomic layers, photoelectron forward scattering by overlying atoms in the lattice causes XPS peak intensities to be enhanced at angles corresponding to nearest neighbor and next-nearest neighbor internuclear axes. Angle resolved XPS should thus be an excellent approach for gaining structural information on, for example, epitaxial overlayers or surface reconstructions.