The calculation of radial integrals for bound-free and free-free transitions

Abstract

An analytical method, already applied to bound-bound and bound-free transitions, is extended to free-free transitions in the field of positive ions. The role of a cut-off factor, intended to cancel the diverging part of the irregular Coulomb functions, as well as the way to obtain photoionisation data for excited states from the extrapolation of free-free results, are carefully discussed.