Analysis of ν2 of H 2S

Abstract

The infrared absorption spectrum of ν 2 of H 2S in the region from 1000 to 1500 cm −1 was obtained with a resolution limit of <0.05 cm −1 on the University of Denver 50-cm FTIR spectrometer system. We have assigned 387 lines due to H 2 32S, 75 lines due to H 2 34S, and 15 lines due to H 2 33S, and have analyzed them using Typke's reduction of Watson's Hamiltonian. Slightly revised ground-state constants for the 32 isotope were obtained from a simultaneous fit of the microwave transitions observed by Helminger, Cook, and De Lucia, combined with weighted averaged ground-state combination differences formed from the infrared bands (010), (020), (100), (001), (110), (011), (210), and (111). The standard deviation for the fit was 0.0018 cm −1 for the infrared data and 0.000032 cm −1 for the microwave lines. Upper-state constants for the 32 isotope were obtained from a least-squares fit of the spectral lines of ν 2, keeping the ground-state constants fixed to the values determined by the combination difference fit. The standard deviation of the (010) line fit was 0.0017 cm −1 for the 32 isotope. Ground-state and upper-state isotopic mass adjustment constants were determined in a simultaneous fit of lines of H 2 33S and H 2 34S, keeping the ground-state and upper-state constants for the 32 isotope fixed.