Relative single- and double-photoionization cross sections of Mg around the2p→nlresonances

Abstract

Using highly monochromatized synchrotron light and the ion time-of-flight method to detect singly and doubly charged magnesium ions, we have measured relative single- and double-photoionization cross sections of Mg from $55\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}58\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, which includes the region of the $2p\ensuremath{\rightarrow}nl$ inner-shell excitations. The resonances were analyzed using Fano profiles and the resonance positions are compared to previously published data. The quantum defect theory is applied to the resonance energies revealing that the published Mg $2{p}_{1∕2}$ and $2{p}_{3∕2}$ thresholds need to be revised. In addition, we have determined the double-to-single photoionization ratio in the $55\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}71\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ region.