Differential cross sections for excitation to the 3s, 3p and 3d states of atomic hydrogen by electron impact at energies from 16.5 to 54 eV

Abstract

The excitation of atomic hydrogen from the ground state to each of the 3s, 3p and 3d states has been studied for incident electron energies from 16.5 to 54 eV. Measurements of total cross sections and differential excitation cross sections (DCSs) for scattered electron angles from 5° to 150° have been made using a variety of coincidence methods. Within the summed experimental uncertainties of about 10% at best from statistical sources and 25% from absolute calibration sources the values calculated using the propagating exterior complex scaling and convergent close-coupling methods show good agreement with observations. DCS calculations for all s, p, d and f final states with n ⩽ 4 are also presented over this energy range and reveal a systematic trend with respect to increasing n, final-state angular momentum and incident energy.