Relativistic plane-wave Born theory and its application to electron-impact excitation

An exact treatment of the relativistic plane-wave Born (RPWB) cross section for electron-impact excitation is provided for an arbitrary atom or ion. This result represents an improvement over the cross section obtained from the widely used Bethe high-energy theory developed in the 1930s. The results obtained from this RPWB approach can be applied to a broad class of problems in fundamental electron-impact scattering theory. As an illustration, the approach is used to approximate the high-l, partial-wave contribution in more accurate calculations of the excitation cross section, a problem which has been lacking a fully relativistic treatment for more than 20 years.