Photoionization Study of S⁴⁺ Ions Using the Modified Atomic Orbital Theory

The single photoionization of S V ions into S VI is investigated in this paper within the framework of modified atomic orbital theory (MAOT). The theoretical resonance energies, quantum defects and effective nuclear charges of the autoionizing Rydberg series 2s²2p⁵3s²nd (¹P₁, ³D₁), 2s²2p⁵3s²ns (¹P₁, ³D₁) and 2s2p⁶3s²np (¹P₁) resulting from the 2p → nd, 2p → ns and 2s → np transitions respectively in the 2s²2p⁶3s² (¹S₀) ground state of S⁴⁺ are reported. The present results are in excellent agreement with experimental synchrotron radiation measurements and theoretical calculations (MCDF and R-matrix) by Mosnier et al. (Phys Rev A 106:033113, 2022). The newly tabulated MAOT data up to n = 40 are relevant for both laboratory and astrophysical plasmas.