NonperturbativeB-splineR-matrix-with-pseudostates calculations for electron-impact ionization-excitation of helium to then=3states ofHe+

Abstract

We present fully differential cross-section ratios for electron-impact ionization of helium without excitation and with simultaneous excitation of the residual ion. The results are obtained from a nonperturbative close-coupling formalism, with the resulting equations being solved by a $B$-spline $R$-matrix-with-pseudostates approach. Very encouraging agreement is obtained with directly measured cross-section ratios for ionization leaving the residual ${\mathrm{He}}^{+}$ ion in either the $1s$ ground state or the $n=3\phantom{\rule{4pt}{0ex}}(3s+3p+3d)$ excited states.