Precision measurements of the 2P1/2−2P3/2 fine-structure splitting in B-like S11+ and Cl12+

Abstract

The fine-structure splitting $1{s}^{2}2{s}^{2}2p {}^{2}{P}_{1/2}{\text{\ensuremath{-}}}^{2}{P}_{3/2}$ transitions in boronlike ${\mathrm{S}}^{11+}$ and ${\mathrm{Cl}}^{12+}$ were experimentally measured with a high precision spectrometer at the Shanghai high-temperature superconducting electron beam ion trap. The $M1$ transition wavelengths for ${\mathrm{S}}^{11+}$ and ${\mathrm{Cl}}^{12+}$ were determined to be 760.9635(29) and 574.1539(26) nm (in air), respectively. Compared to the previously observed results, the accuracies of current experimental results are improved by more than ten times and 200 times for ${\mathrm{S}}^{11+}$ and ${\mathrm{Cl}}^{12+}$, respectively. Additionally, the $M1$ transition energies in ${\mathrm{S}}^{11+}$ and ${\mathrm{Cl}}^{12+}$ were evaluated within the ab initio QED framework to compare with the experimental data. The present experimental results agree with the theoretical calculations and provide a possibility to test QED effects and correlation effects with high accuracy in few-electron highly charged ions.