Electron-impact ionization cross sections for the xenon isoelectronic sequence

Abstract

Cross sections are presented for the direct electron-impact ionization of the 5p, 5s, and 4d subshells of the ground state of the first six members of the xenon isoelectronic sequence. The calculations were performed in a distorted-wave Born-exchange approximation including the effects of term-dependent partial waves in the ejected-electron channel and ground-state electron correlation. Shape resonances were found to significantly enhance the cross sections at low incident electron energies for Xe, ${\mathrm{Cs}}^{+}$, and ${\mathrm{Ba}}^{2+}$. Term dependence in the 5$p^5$kd and 4$d^9$kf ejected-electron channels was also significant for these ions. Ground-state correlation was somewhat less influential, and affected the cross section only when ejected-electron term dependence was also significant.