Electron impact excitation of H and He+. VI. Excitation of the n=3 levels

Abstract

For pt.V see ibid., vol.8, p.1073 (1975). Electron impact excitation of the n=3 levels of atomic hydrogen is investigated by generalizing the DWPO II approximation (McDowell et al.) to 1s to nlm_l transitions. Results are presented, at energies from threshold to 500 eV, for total cross sections for each 1s to 3l (l=0,1,2) transition, total n=3 cross sections, and the cross section for H alpha production. They are compared, where possible, with experiment. Results for the polarization of H alpha emitted at 90 degrees to the incident beam are given in Born and DWPO II models, and shown to be inconsistent with experiment. Differential cross sections for individual and total n=3 transitions are tabulated at selected angles and energies. Further experimental and theoretical work is suggested.