Electron-impact ionization ofLi+

Abstract

Electron-impact ionization cross sections for ${\mathrm{Li}}^{+}$ are calculated using the $R$ matrix with pseudostates method and time-dependent close-coupling theory. The largest $R$-matrix calculation includes 11 spectroscopic states from the configurations ${1s}^{2},$ $1s2l,$ and $1s3l;$ an additional 56 pseudostates from the configurations $1s\mathrm{n\ifmmode \bar{}\else \={}\fi{}}l$ with $\mathrm{n\ifmmode \bar{}\else \={}\fi{}}=4--10$ and $l=0--3;$ and enough continuum orbitals to adequately describe incident energies up to 175 eV. The largest time-dependent close-coupling calculations involved 16 partial differential equations on a $300\ifmmode\times\else\texttimes\fi{}300$ point radial lattice. The nonperturbative $R$ matrix with pseudostate and time-dependent close-coupling calculations, as well as perturbative distorted-wave calculations, are in good agreement with the crossed-beams experimental measurements of Lineberger et al. [Phys. Rev. 141, 151 (1966)], but are slightly above the Peart and Dolder [J. Phys. B 2, 872 (1968)] and M\"uller et al. [Phys. Rev. Lett. 63, 758 (1989)] measurements.