Classical calculations on electron capture

The classical theory of Thomas on electron capture from heavy atoms by fast nuclei is considered. A modification is introduced. It is found that the predictions of the modified theory are in quite good accord with the measurements of Barnett and his associates. The extent to which the scaled experimental data on a number of gases may be represented by a single curve is striking. Capture from light atoms is also discussed. The approximations made in the classical impulse approximation are here unsatisfactory. A simple classical theory of symmetrical resonance capture in slow encounters is developed. It is remarkably successful.