Semiempirical Cross-Sections and Rates for Excitation and for Ionization of Hydrogenic Ions by Electron Impact

Semiempirical electron-impact cross-sections and rates are given for hydrogenic ions of any Z both for ionization and for excitation of the type n -`n', where n and n' are the initial and final principal quantum numbers. The results are written in a form similar to and involving the same parameters as our earlier work on hydrogen. For ionization, the results are quite similar to Percival's proposal; however, for excitation they are usually slightly larger for n n + 1 transitions and considerably larger for n H fl' > fl + 1 transitions than most previous proposals.