Resonance Structures in Photoionization of $S^+$

Resonance structures in the photoionization of $S^+$ for the removal of a 3p or 3s electron from the ground 3s$^2$3p$^3$~$^4$S$^o$ and excited metastable $^2D^o$ and $^2P^o$ states have been studied in the B-spline R-matrix approach. The non-orthogonal orbitals are used for an accurate description of the $S^+$ initial bound states, the final $S^{2+}$ ion plus photoelectron states and $S^{2+}$ ionic thresholds. Calculations have been carried out in 17- and 27-state close-coupling approximations. The relativistic effects have been considered in the Breit- Pauli Hamiltonian. Photoionization cross sections are dominated by $3s^23p^2(^1D)ns~^2D$, $3s^23p^2(^1D)nd~^2F$, $^2D$, $^2P$ and $3s3p^3(^5$S$^o$,~$^3$S$^o$,~$^3$D$^o$,~$^3$P$^o$)np~$^4$P Rydberg series of resonances. Our results will be compared with merged ion-photon beam experiment.