The data set is based on the one described in
(1) S. P. Belov, K. M. T. Yamada, G. Winnewisser, L. Poteau, R. Bocquet, J. Demaison, O. Polyanski, and M. Yu. Tretyakov, 1995, J. Mol. Spectrosc. 173, 380.
The data set includes one line each from
(2) R. E. Cupp, R. A. Kempf, and J. J. Gallagher, 1968, Phys. Rev. 171, 60,
and from
(3) C. Huiszoon, 1970, Rev. Sci. Instrum. 42, 477,
as well as extensive data from
(4) P. Helminger, R. L. Cook, and F. C. De Lucia, 1972, J. Chem. Phys. 56, 4581.
Also included in the fit are far-infrared transitions from
(5) K. M. T. Yamada and S. Klee, 1994, J. Mol. Spectrosc. 166, 395.
Additional far-infrared transitions exceeding the data set of (5) were taken from
(6) J.-M. Flaud, C. Camy-Peyret, and J. W. C. Johns, 1983, Can. J. Phys. 61, 1462.
As emphasized in (5), the uncertainties in that work were not absolute. In the present calculations the numbers have been reduced by a factor of 5. This is probably still a too little, but 10 seems a bit too much. The original uncertainties from (2) and (3) were employed. One line from (4) with large residual in (1) was omitted, and the uncertainties of the TuFIR data from (1) were doubled. A very small number of frequencies from (6) whose residuals exceeded three times the uncertainties were omitted from the fit.
Transition frequencies with uncertainties larger than 200 kHz have not been merged. The predictions should be reliable as long as the uncertainties do not exceed 5 MHz by far.
At low temperatures, it may be necessary to discern between ortho-H₂S and para-H₂S. The ortho and para states are described by K_a + K_c being odd and even, respectively. The nuclear spin-weights are 3 and 1 for ortho-H₂S and para-H₂S, respectively. The J_KaKc = 1₀₁ is the lowest ortho state. It is 13.7463 cm^–1 above ground. Aug. 2011: separate para and ortho predictions are available along with separate para and ortho partition function values. Note: the spin-weight of 3 for the separate ortho predictions has been eliminated.
The dipole moment is from
(7) R. Viswanathan and T. R. Dyke, 1984, J. Mol. Spectrosc. 103, 231.