Photoionization cross sections of the aluminumlikeSi+ion in the region of the2pthreshold (94–137 eV)

Abstract

We present measurements of the absolute photoionization cross section of the aluminumlike ${\mathrm{Si}}^{+}$ ion over the 94--137 eV photon energy range. The measurements were performed using the merged-beam setup on the PLEIADES beamline at the SOLEIL synchrotron radiation facility. Signals produced in the ${\mathrm{Si}}^{2+}$ and ${\mathrm{Si}}^{3+}$ photoionization channels of the $2p$ subshell of the ${\mathrm{Si}}^{+}$ ion from both the $1{s}^{2}2{s}^{2}2{p}^{6}3{s}^{2}3p{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2,3/2}$ ground levels and the $1{s}^{2}2{s}^{2}2{p}^{6}3s3{p}^{2}{\phantom{\rule{0.16em}{0ex}}}^{4}P$ metastable levels were observed. Absolute cross sections were determined. Calculations of the $2p$ inner-shell photoionization cross sections were carried out using the multiconfiguration Dirac-Fock and Dirac-Coulomb R-matrix theoretical approaches and are compared with experiment.