Electron Capture and Excitation inHe+-He Collisions

Abstract

The processes of excitation and capture of electrons in ${\mathrm{He}}^{+}$-He collisions have been theoretically investigated. An expansion in terms of products of atomic wavefunctions has been used which takes account of the possibilities of the excitation of the helium atom to the $2^{1}S$ and $2^{3}S$ states and the capture of an electron into the ground, $2^{1}S$, and $2^{3}S$ states. The probabilities for the different processes have been computed for several impact parameters over the energy range 0.6 to 40 keV. The calculated total cross sections for excitation to and capture into either of the above excited states in the above-mentioned energy range are found to be almost equal. The sum of the calculated total cross sections for electron capture in the ground, $2^{1}S$, and $2^{3}S$ states of helium agrees fairly well with experimental results.