Photoionization of helium between theN=2andN=5thresholds ofHe+:Partial differential cross sections

Abstract

Photoionization excitation of helium has been performed employing the R-matrix method with a 20-term target representation for incident photon energies between the $N=2$ and $N=5$ thresholds (69--76.8 eV) of the ${\mathrm{He}}^{+}$ ion. Partial differential cross sections for photoionization leaving the ${\mathrm{He}}^{+}$ ion in the $N=2,3,4$ levels at emission angles $0\ifmmode^\circ\else\textdegree\fi{}$ and in the $N=2$ level $90\ifmmode^\circ\else\textdegree\fi{}$ are provided. Our results to ${\mathrm{He}}^{+}$ in the $N=2$ state give fairly good agreement with the available experimental data and theoretical calculations below the $N=3$ threshold. Between the $N=3$ and $N=5$ thresholds of the ${\mathrm{He}}^{+}$ ion, our results for ${\mathrm{He}}^{+}$ in the $N=2,3,4$ states still agree with experiment qualitatively.