Photoionization of magnesium including double excitations.

Abstract

The multiconfiguration relativistic random-phase approximation is applied to the photoionization of magnesium. Autoionization resonances between the 3${\mathit{s}}_{1/2}$ and 3${\mathit{p}}_{1/2}$ ionization thresholds are investigated. The main feature of our results is exhibited by three Rydberg series: the broad 3pns $^{1}$${\mathit{P}}_{1}$ series, the narrow 3pnd $^{1}$${\mathit{P}}_{1}$ series, and the 3pns $^{3}$${\mathit{P}}_{1}$ series caused by the fine-structure splittings. Our predictions of the resonance positions are in excellent agreement with experiment, and are consistent with other calculations. For photon energies above the 3${\mathit{p}}_{3/2}$ threshold, cross sections and spin polarizations of photoelectrons from the ionization channels Mg \ensuremath{\rightarrow}${\mathrm{Mg}}^{+}$${(}^{2}$${\mathit{S}}_{1/2}$)+${\mathit{e}}^{\mathrm{\ensuremath{-}}}$, Mg \ensuremath{\rightarrow}${\mathrm{Mg}}^{+}$${(}^{2}$${\mathit{P}}_{1/2}^{\mathit{o}}$)+${\mathit{e}}^{\mathrm{\ensuremath{-}}}$, and Mg \ensuremath{\rightarrow}${\mathrm{Mg}}^{+}$${(}^{2}$${\mathit{P}}_{3/2}^{\mathit{o}}$)+${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ are obtained and compared with other theoretical results.