Photoionization of the 3s23p43P and the 3s23p41D,1S states of sulfur: Experiment and theory

Abstract

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 compared with 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.