Very accurate terahertz transition frequencies were added with respect to the second entry from Feb. 2008. These were taken from
(1) H. S. P. Müller, A. Maeda, S. Thorwirth, F. Lewen, S. Schlemmer, I. R. Medvedev, M. Winnewisser, F. C. De Lucia, and E. Herbst, 2019, Astron. Astrophys. 621, Art. No. A143.
With respect to the Feb. 2006 entry, extensive millimeter and submillimeter transitions were published by
(2) A. Maeda, I. R. Medvedev, M. Winnewisser, F. C. De Lucia, E. Herbst, H. S. P. Müller, M. Koerber, C. P. Endres, and S. Schlemmer, 2008, Astrophys. J. Suppl. Ser. 176, 543.
In addition, ground state combination differences were taken from
(3) D. J. Clouthier, G. Huang, A. G. Adam, and A. J. Merer, 1994, J. Chem. Phys. 101, 7300.
The data have been kindly provided by the first author.
For the first entry, several microwave and millimeter-wave transitions frequencies were taken from
(4) D. R. Johnson, F. X. Powell, and W. H. Kirchhoff, 1971, J. Mol. Spectrosc. 39, 136;
some of these were already reported in
(5) D. R. Johnson and F. X. Powell, 1970, Sience 169, 679.
Few additional lines were taken from
(6) V. Beers, G. P. Klein, W. H. Kirchhoff, and D. R. Johnson, 1972, J. Mol. Spectrosc. 44, 553.
The J = 1 – 1 transition was reported by
(7) B. Fabricant, D. Krieger, and J. S. Muenter, 1977, J. Chem. Phys. 67 1576.
Pure rotational transitions obtained by FT-FIR spectroscopy were also used in the fit. The data set is described by
(8) D. McNaughton and D. N. Bruget, 1993, J. Mol. Spectrosc. 159, 340.
The transition frequencies have been kindly provided by the first author. Several of these were omitted in (1) because of more accurate data. Some data in (4) and (6) were replaced by more accurate data in (2) from (2). Details on the data and parameter sets are available in (1).
R-branch transitions with uncertainties larger than 50 kHz have not been merged. Predictions with uncertainties of less than 1 MHz should be sufficiently reliable.
The dipole moment was measured in (7).
At low temperatures, it may be necessary to discern between ortho-H₂CS and para-H₂CS. The ortho states are described by K_a odd, the para states by K_a even. The nuclear spin-weights are 3 and 1 for ortho-H₂CS and para-H₂CS, respectively. The J_KaKc = 1₁₁ is the lowest ortho state. It is 10.2818 cm^–1 above ground.
Dec. 2011: Separate para and ortho predictions are available along with separate para and ortho partition function values.
The ¹H hyperfine splitting may be resolved at low temperatures, low frequencies, and for low values of J. Therefore, a separate hyperfine calculation is provided up to J = 7 for transitions with ΔJ = 0 and K_a = 1 along with separate ortho partition function values.