The production and spectroscopy of excited sulfur atoms from the two-photon dissociation of H2S

Abstract

Ground (3PJ) and excited state (1D2, 1S0) sulfur atoms have been produced by the two-photon photodissociation of H2S in the wavelength range 285–316 nm. The resultant sulfur atoms undergo 2+1 resonance enhanced multiphoton ionization (REMPI) at selected laser wavelengths. The initial and final ion states in the 2+1 REMPI process have been determined through the analyses of the REMPI spectrum (laser wavelength scan) and the REMPI-PES taken at the atomic resonances. The intermediate states accessed in the two-photon excitations have been assigned. Several transitions which originate from the 1S0 excited state of atomic sulfur have been observed. The intermediate states of these transitions lie above the ionization continuum and are depleted competitively by autoionization and further photon absorption. Extremely pure state selection of ground and excited sulfur atomic ions is demonstrated at several of the two-photon resonances. Evidence of configuration interaction between the 6p 3P1, 6p 5P1, and 4p 1P1 levels is presented.

Resonance-enhanced multiphoton-ionization photoelectron spectroscopy of even-parity autoionizing Rydberg states of atomic sulphur

“…The fact that no transition from the 3 P 0 level to this state was observed in the present study, and that no transitions from the 1 S 0 state have occurred in previous two-photon excitation studies, 7 confirms the assignment of this state as 1 P 1 . However, the photoelectron spectra recorded at two-photon energies of 87 624.1 and 78 385.6 cm Ϫ1 both show a 2 D o : 2 P o ratio of 1:7, which suggests that the configuration is ( 2 P o )4p rather than ( 2 D o )5p.…”

“…Detailed wavelength scans employing kinetic energyresolved electron detection were recorded in order to obtain accurate estimates for the relative intensities of the transitions from the 3 P 1 and 3 P 2 levels to these states ͑see Fig. 5͒ 7 However, the present study shows that the ( 2 P o )4p 3 D state lies at a much lower energy.…”

“…7 Here, an alternative assignment is proposed. The fact that the excited state is observed to be accessible from the 3 P 2 , 3 P 1 , and 3 P 0 levels implies that it must have a total angular momentum Jϭ2 ͑Jϭ0↔Jϭ1, two-photon transitions are strictly forbidden͒.…”

“…The transitions from the 1 D 2 state can easily be recognized as such by their photoelectron spectra. 7 The line positions of the transitions are given in Table III. Some of the energy levels have been reported previously, accessed from either the 1 D 2 or 1 S 0 excited state.…”

“…2 Even-and odd-parity excited states of the atom have been extensively investigated by one-photon vacuum ultraviolet absorption [3][4][5] and photoionization 6 studies, and by (2ϩ1) resonance enhanced multiphoton ionization ͑REMPI͒ spectroscopy. [7][8][9][10][11] Recently we reported on a (2ϩ1) REMPI-photoelectron spectroscopy ͑REMPI-PES͒ study of the S atom, in which Rydberg states converging upon the lowest ionic state were investigated. 12 In this study, some 20 hitherto unobserved even-parity Rydberg states belonging to the ( 4 S o )n f 3 F and ( 4 S o )np 3 P series have been characterized.…”