Absorption spectrum of the H₂S molecule in the vacuum ultraviolet region

Abstract

The optical absorption spectrum of the H2S molecule in the region from 2050 to 1150 Å has been studied by a photographic method, using the radiation from a 1.3-GeV electron synchrotron as a background source. Numerous bands including those due to dipole forbidden transitions are observed in the spectrum. Five types of Rydberg series are assigned to electronic transitions from the outermost 2b1 orbital to the d-like orbitals, three types to the p-like orbitals, and one type to the s-like orbital. The quantum defects of these transitions and a series limit of 84 417 ± 8 cm−1 (10.466 ± 0.001 eV) were determined using the extended Rydberg series. The first member of the A Rydberg series splits into four bands, which is discussed with jj coupling scheme. The upper state of the 2000-Å (6.20-eV) broad band is assigned to the (2b1)−1 (6a1/4sa1) 1B1 state which is predominantly of valence orbital character. Transitions to vibrationally excited state were also investigated and the limit to which the (100) vibrationally excited Rydberg series converges was determined to be 86 882 ± 20 cm−1 (10.772 ± 0.003 eV). The results obtained in this experiment are compared with theoretical calculations.

Vertical Excitation Energies and Ionization Potentials of H2S. A Size-Consistent Self-Consistent Singles and Doubles Configuration Interaction (SC)2-MR-SDCI Calculation

“…The present (SC) 2 theoretical values are 9.55 eV for the 1 B 1 (6s) state and 9.81 eV for the 1 B 1 (7s) state, in better agreement with those of ref 4 than the ones of ref 10, but still slightly too low in magnitude. The calculations of D&L lead to VEE's that conform well with the experimental values of Masuko et al 4 The 5a 1 f 4s excitation occurs among the lowest 1 A 1 f 1 A 1 transitions. The 1 A 1 (4s) state is the only one reported in Table 2 that is dominated by an excitation from the 5a 1 MO.…”

“…Table 2 clearly shows the grouping of the different Rydberg series: 4s, 4p, 3d, 5s, .... The present VEE for the 1 B 1 (4s) state, of about 6.5 eV, is 0.2 eV higher than that of Masuko et al 4 However, more recent works report a wide band in this region, 8 located between 4.5 and 6.52 eV (a detailed compilation of the experimental values is given by Diercksen and Langhoff 7 ). Abuain et al 6 pointed out the existence of a maximum in the spectrum at 6.4 eV, which they assigned to a transition to a 1 B 1 state.…”

“…While Ashfold et al 10 and Mayhew et al 8 report values of 9.27 and 9.77 eV, respectively, the ones measured by Masuko et al 4 were 9.66 for 1 B 1 (6s) and 9.94 eV for 1 B 1 (7s). The present (SC) 2 theoretical values are 9.55 eV for the 1 B 1 (6s) state and 9.81 eV for the 1 B 1 (7s) state, in better agreement with those of ref 4 than the ones of ref 10, but still slightly too low in magnitude.…”

Theoretical study of molecular properties of low-lying electronic excited states of H2O and H2S

“…We found no experimental data for the triplet 3 A 2 and 3 B 1 states of H 2 S. Experimental value for the 1 A 2 is rather uncertain [56]. Our vertical excitation energy for the 1 B 1 state agrees with experimental value reasonably well, differing by less than 0.08 eV.…”

Sulfur isotopic fractionation in vacuum UV photodissociation of hydrogen sulfide and its potential relevance to meteorite analysis

“…VUV Photochemistry and Predissociation Dynamics of H 2 S. Absorption spectra of H 2 S exhibit several Rydberg series in the VUV spectral region (up to 160 nm) and converge to the ionization limit beyond 90 nm (30)(31)(32)(33)(34). There are several experimental and theoretical spectroscopic studies (35)(36)(37)(38)(39)(40)(41) that describe the photodissociation dynamics of H 2 S at the experimental VUV wavelengths (i.e., 121.6, 139.1, and 157.6 nm) explored in the present study.…”