Photoionization cross sections of the aluminumlike Si+ ion in the region of the 2p threshold (94-137 eV)

We present measurements of the absolute photoionization cross section of the aluminumlike 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 Si2+ and Si3+ photoionization channels of the 2p subshell of the Si+ ion from both the 1s(2)2s(2)2p(6)3s(2)3p P-2(1/2,3/2) ground levels and the 1s(2)2s(2)2p(6)3s(3)p(2 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.