Excitation of highly excited hydrogenic ions and atoms by charged particles III

For pt. II see ibid, Vol 4, 918-31. Heisenberg's form of the correspondence principle has been used to calculate collisional excitation cross sections for transitions between two highly excited levels. An impact parameter formulation of the sudden approximation and first order perturbation theory has been used. The range of incident energies for which the results are given 2M/m e mod ZZ' mod n<E/Ryd<M/m e Z' 2 is determined by the condition that these approximations should have a common region of validity. Where possible the authors have checked these approximations using a more general correspondence principle. Results for the hydrogen atom (Z=1) have been previously reported. The cross-section is obtained in analytic form and is at worst in error by about 20%.