Photoionization of the $3s^23p^4~ ^3P$ and the $3s^23p^4~^1D,~^1S$ states of sulfur: experiment and theory

摘要

Photoionization of neutral atomic sulfur in the ground and metastable stateswas studied experimentally at a photon energy resolution of 44 meV FWHM.Relative cross section measurements were recorded by using tunable vacuumultraviolet (VUV) radiation in the energy range 9 -- 30 eV obtained from alaser-produced plasma and the atomic species were generated by photolysis ofmolecular precursors. Photoionization of this atom is characterized by multipleRydberg series of autoionizing resonances superimposed on a directphotoionization continuum. A wealth of resonance features observed in theexperimental spectra are spectroscopically assigned and their energies andquantum defects tabulated. The cross-section measurements are compared withstate-of-the-art theoretical cross-section calculations obtained from the DiracCoulomb R-matrix method. Resonances series in the spectra are identified andcompared indicating similar features in both the theoretical and experimentalspectra.