Photoionization of the 3s23p4 3P and the 3s23p4 1D, 1S states of sulfur: Experiment and theory

Photoionization of neutral atomic sulfur in the ground and metastable states was studied experimentally at a photon energy resolution of 44 meV (full width at half maximum). Relative cross section measurements were recorded by using tunable vacuum ultraviolet radiation in the energy range 9-30 eV obtained from a laser-produced plasma and the atomic species were generated by photolysis of molecular precursors. Photoionization of this atom is characterized by multiple Rydberg series of autoionizing resonances superimposed on a direct photoionization continuum. A wealth of resonance features observed in the experimental spectra are spectroscopically assigned and their energies and quantum defects tabulated. The cross section measurements are comparedwith state-of-the-art theoretical cross section calculations obtained from the Dirac Coulomb R-matrix method. Resonance series in the spectra are identified and compared, indicating similar features in both the theoretical and experimental spectra.