Two-photon induced fluorescence and resonance-enhanced ionization of sulfur atoms

Two-photon induced fluorescence and resonance-enhanced photoionization have been observed in atomic sulfur originating from both the ³P_2,1,0 and the ¹D₂ states. Sulfur atoms are generated by the sequential multiphoton dissociation of CS₂ at probing wavelengths. The two-photon absorption process involves the 3 ³P_2,1,0 → 4 ³P_2,0,1 or the 3 ¹D₂ → 4 ¹F₃ transitions with resolution of the individual J″ → J′ transitions in most cases. Intensities of the 3³P_J″ → 4 ³P_J′ transitions have been compared with Hartree-Fock calculated transition probabilities from the analogous transitions in atomic oxygen. Photoionization is observed in a three-photon (two to resonance) ionization originating from the ³P_2,1,0 and the ¹D₂ states. Induced fluorescence is observed at 167 and 180 nm which is dipole-allowed radiation from the intermediate ³S⁰₁ and ¹D⁰₂ states, respectively.