Low-energy scattering of charged particles.

Abstract

The off-energy-shell T-matrix for two charged particles is studied in the low momentum limit (k- 0). The T-matrix for a Coulomb interaction (To) is usually considered as the limit of the amplitude for a screened potential (T~) when the screening is removed. We show that this statement is not true for small enough energies. For an attractive interaction T0 and T5 differ significantly when k-0. T c behaves as k-~, while T~ keeps its k -~ behaviour even when the screening is turned off. We note that this is an effect which would be observed in ion-atom collisions when one electron is ejected from the atom and captured into a continuum state of the ion.