Abstract

The high resolution infrared spectra of hydrogen sulfide, H₂^MS (M = 32,33,34,36) in the natural abundance (95.041% of H₂³²S, 0.748% of H₂³³S, 4.196% of H₂³⁴S and 0.015% of H₂³⁶S), were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zürich prototype ZP2001) and analyzed in the ν₂ fundamental band region (700–1800 cm⁻¹). In the experimental spectra 1564, 1019, and 685 transitions were assigned to the ν₂ bands of H₂³²S, H₂³⁴S and H₂³³S (the maximum values of the quantum numbers are J^max./K_a^max. = 24/17, 20/14, 17/14). The subsequent weighted fits of experimentally assigned transitions were made with the Watson Hamiltonian and a set of parameters which reproduces the initial 333/249/216 infrared ro-vibrational energy values has been obtained from the assigned experimental line positions with the root mean square deviations of d_rms = 2.2 x 10⁻⁴ cm⁻¹, 1.7 x 10⁻⁴ cm⁻¹ and 1.5 x 10⁻⁴ cm⁻¹ for the H₂³²S, H₂³⁴S and H₂³³S isotopologues. Additionally, 703, 182 and 23 transitions with the values of quantum numbers J^max./K_a^max. = 18/14, 14/8 and 9/6 belonging to the 2v₂ − v₂ hot bands of H₂³²S, H₂³⁴S and H₂³³S (for the first time for the hot bands of the H₂³⁴S and H₂³³S species) were assigned in the experimental spectra. Rotational parameters of the ground vibrational state of H₂³⁶S were re-determined, and, for the first time, 103 transitions (J^max. = 11, K_a^max. = 8) of the ν₂ band of H₂³⁶S were assigned in the experimental spectra. An analysis of ro-vibrational line strengths of 61 experimental isolated unsaturated and not too weak lines of the ν₂ band of H₂³²S was made (J^max. = 9, K_a^max. = 8), and five effective dipole moment parameters were obtained from the fit which reproduce the initial experimental line intensities with the d_rms = 1.4%. An analogous analysis was performed for the H₂³⁴S and H₂³³S isotopologues. The half-widths analysis was made on the basis of the multi-spectrum fit with the Hartmann-Tran line profile, and self-pressure broadening coefficients were estimated for a few tens of lines for the three most abundant isotopologues.