ELASTIC AND INELASTIC-SCATTERING OF ELECTRONS FROM POTASSIUM

We have examined elastic and inelastic scattering of electrons from po tassium. For the case of elastic scattering, we have compared potentia l scattering theory and perturbation theory. If one wishes to use the potential scattering approach, it is shown that both the non-local eff ects of polarization and absorption must be properly modelled to get a ccurate elastic differential cross sections. The second-order distorte d wave results for elastic scattering and excitation of the (4p)2P and (5p)2P states are compared with existing experimental data and a very recent close coupling calculation for energies between 7 and 100 eV.