Radiative and Auger transitions of K-shell excited resonance states in boron-like sulfur ion

Abstract

<sec>Non-relativistic energy values and wave functions of the K-shell excited resonance states 1s2s<sup>2</sup>2p<sup>2</sup>, 1s2s2p<sup>3</sup>, 1s2p<sup>4 2, 4</sup><i>L</i> (<i>L</i> = S, P, D) in boron-like sulfur ion are calculated in the frame of multi-configuration saddle-point variation method. The electron correlation effects are considered by the expansion of configuration wave function. The wave functions are constructed and optimized by the orbital-spin angular momentum partial waves selected based on the rule of configuration interaction. To saturate the wave functional space and to improve the non-relativistic energy, the restricted variational method is used to calculate the restricted variational energy. Then, the mass polarization effect and relativistic correction are calculated by the perturbation theory. The quantum electrodynamics (QED) effect and higher-order relativistic correction are considered by the screened hydrogenic formula. Furthermore, the energy shift originating from the interaction between closed channel and open channel is also calculated. Finally, the accurate relativistic energy levels for these resonance states are obtained by adding the non-relativistic energy and all corrections.</sec><sec>Using the optimized wave functions, the line strengths, oscillator strengths, radiative transition rates and transition wavelengths of electric-dipole transitions for the K-shell excited resonance states in boron-like sulfur ion are systematically calculated. In this work, the oscillator strengths and transition rates are given in the length, velocity, and acceleration gauges. The good agreement among the three gauges reflects that the calculated wave functions are reasonably accurate. The calculated radiative transition rates and transition wavelengths are compared with other theoretical data. Good agreement is obtained except the transition: 1s2s(<sup>3</sup>S)2p<sup>3</sup> <sup>2</sup>P<sup>o</sup>→1s2<sup>2</sup>s2p<sup>2 2</sup>D. The deviation between our theoretical result and the MCDF theoretical value is about 46%, which needs further verifying. The Auger rates, Auger branching ratios, and Auger electron energy values of the important decay channels of the K-shell excited states are calculated by the saddle-point complex-rotation method. The calculated Auger rates and Auger electron energy values are also in good agreement with the corresponding reference data. For some K-shell states, the related energy levels and Auger branching ratios are reported for the first time. The present calculations results will provide valuable theoretical data for the calibration of spectral lines and Auger electron spectra in the relevant experiments.</sec>