Photoionization of doubly-charged scandium ions

Abstract

Photoionization cross-section calculations are performed for the ground $([\mathrm{Ne}]3{s}^{2}3{p}^{6}3d\phantom{\rule{0.2em}{0ex}}^{2}D_{3∕2}^{e})$ and the first two excited states $([\mathrm{Ne}]3{s}^{2}3{p}^{6}3d\phantom{\rule{0.2em}{0ex}}^{2}D_{5∕2}^{e})$, $([\mathrm{Ne}]3{s}^{2}3{p}^{6}4s\phantom{\rule{0.2em}{0ex}}^{2}S_{1∕2}^{e})$ of doubly-charged scandium $({\mathrm{Sc}}^{2+})$ for photon energies from threshold to $68.0\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The discrete ${\mathrm{Sc}}^{3+}$ orbitals are generated using the computer program AUTOSTRUCTURE; 24 configurations are included in the configuration-interaction calculation for ${\mathrm{Sc}}^{3+}$. In addition to the nonrelativistic (LS-coupling) $R$-matrix, we have used the relativistic (Breit-Pauli) $R$-matrix method to carry out the calculations to focus on relativistic effects. Relativistic and nonrelativistic results are compared to demonstrate the influence of relativistic effects. The prominent $3p\ensuremath{\rightarrow}3d$ giant resonances are analyzed and identified, and our calculated positions and widths are compared with experimental results. Total oscillator strength calculations suggest that the experimental cross section is too small and should be multiplied by a factor of 1.63; with this factor, rather good agreement between theoretical and experimental cross section is found.