Investigation of threshold behaviour of ionisation cross sections

Abstract

The threshold behaviour of differential and total electron-atom ionisation cross sections is investigated by means of the limit procedure in the integral expression of the ionisation amplitude. The case of total angular momentum L=O is considered for which the integral expression of the amplitude is derived. The semiclassical final-state wavefunction is investigated by means of numerical integration. The results confirm the non-linear threshold law found by Wannier and uniform distribution of electron energies.