Electron Impact Excitation of the11S→31PTransition in Helium

Abstract

In the first direct application of the electron-photon coincidence technique for differential cross-section measurements, experimentally determined ratios of the differential cross sections for the electron impact excitation of the $1{}_{}{}^1{}_{}{}^{}S\to 2{}_{}{}^1{}_{}{}^{}P$ to the $1{}_{}{}^1{}_{}{}^{}S\to 3{}_{}{}^1{}_{}{}^{}P$ transitions are presented at 30 and 40 eV incident electron energies. Differential cross sections for the $1{}_{}{}^1{}_{}{}^{}S\to 3{}_{}{}^1{}_{}{}^{}P$ transitions are derived by normalizing these ratios to available experimental differential cross sections for the $1{}_{}{}^1{}_{}{}^{}S\to 2{}_{}{}^1{}_{}{}^{}P$ transition.