ELECTRON-EMISSION DIFFRACTION AND X-RAY-ABSORPTION IN THE PRESENCE OFCOULOMB-LIKE POTENTIALS - THEORETICAL FORMULATION IN THE MUFFIN-TIN POTENTIAL APPROACH

Electron emission diffraction and x-ny absorption in the presence of a n unscreened excited atom core hole-responsible for a long-range Coulo mb force distorting the outgoing electron waves-are described within t he muffin-tin potential model by means of the Green's operator multipl e-scattering formalism: a case especially relevant for molecules and p olyatomic clusters. The approach has the merit of allowing analytical and closed-form expressions to be obtained for all amplitudes and of y ielding the possibility of expanding the scattering amplitudes in mult iple-scattering terms. The treatment is mathematically consistent avoi ding the appearance, in the expanded scattering amplitudes, of terms w hich are either indefinite or divergent.