The semiclassical and shake-down models for post-collision interaction

The consistency of the semiclassical and the shake-down models for post-collision interaction have been tested with measured ejected-electron spectra resulting from the (2s2)1S and the (2s2p)3P autoionising states of He excited by electrons. This was done by comparing spectra measured in two different modes of operation of the electron spectrometer with corresponding model calculations. Although differences between the calculated model spectra and the measurements are observed, this consistency appears to be fairly good. It is shown that for incident energies in the threshold region exact Coulomb wavefunctions have to be used in the shake-down model. It is proved that both models are essentially identical; differences arise from different approximations for the final-state wavefunctions and the overlap integral in the models. (author)