Key points are not available for this paper at this time.
The general formula is derived by considering the model of a single electron moving in a central field. Approximate bound–state radial functions, accurate for large radial distances, may be obtained once the effective quantum numbers | (=n^) | are known. Bates and Damgaard have shown that such functions may be used to obtain good estimates for bound–bound transition integrals. For bound–free transitions use is made of approximate free-state radial functions having exact asymptotic forms, their phases being given by |=| where μ is the extrapolated quantum defect (|=n-|).
Burgess et al. (Mon,) studied this question.