SPHERICAL WAVE CORRECTIONS IN XAFS

Spherical wave corrections in XAFS (x-ray absorption fine structure) are discussed using a new high-energy approximation based on asymptotic expansions. This approximation replaces the plane-wave approximation and is found to be in good agreement with exact treatments almost to the absorption edge. With this formulation the single-scattering XAFS formula is recovered in terms of distance-dependent back-scattering amplitudes. Multiple-scattering contributions in XAFS and spherical wave corrections in angular resolved photoemission are treated similarly