Electron-impact excitation of the12S→22S+22Plevels of atomic hydrogen at 30, 40, 50, 54.4, and 100 eV

Abstract

Normalized experimental differential cross sections for the electron impact excitation of the $1{}^{2}\stackrel{\ensuremath{\rightarrow}}{S}2{}^{2}S+2{}^{2}P$ levels of H at 30, 40, 50, 54.4, and 100 eV incident energies are presented. Ratios of scattering intensities of electrons incident on a target mixture of H and He and having excited the H $(n=2)$ and He $(n=2)$ levels are measured using electron-energy-loss spectroscopy. These intensity ratios are normalized to available, accurate, experimental excitation differential cross sections for He $(n=2)$ [except at 54.4 eV, where theoretical He $(n=2)$ differential cross sections are used] to obtain relative differential cross sections for electron impact excitation of the H $(n=2)$ manifold. The relative H $(n=2)$ differential cross sections are placed on an absolute scale by determining the H/He mixture ratio using energy-loss spectra taken at 200 eV and 25\ifmmode^\circ\else\textdegree\fi{} scattering angle, and normalizing to accurate theoretical H $(n=2)$ and He $(n=2)$ differential cross sections at this energy and scattering angle. Comparisons with available calculations and measurements are made.