Excitation of Atoms by Electron Impact: Current Status and Future Prospects

Abstract

In recent years, much progress has been made in the experimental and theoretical studies of atomic collision processes. The preparation of spin-polarized collision partners and the measurement of orientation, alignment, and spin polarization parameters after the collision has enabled experimentalists to perform very detailed tests of theoretical models. In some cases, even “complete” or “perfect” experiments were performed, where all independent scattering amplitudes for a particular atomic collision process were determined experimentally. Since these amplitudes contain the maximum, quantum mechanically available information about the scattering event, the results of such measurements have presented important benchmark data for the assessment and further development of computer simulation programs. A general framework and a unified terminology for the description of spin-dependent electron—atom scattering has now been developed,¹ and the available experimental and theoretical data have been reviewed.²