Very accurate millimeter to terahertz transition frequencies were added with respect to the first entry from Feb. 2006. 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, transition frequencies were taken from
(2) D. R. Johnson, F. X. Powell, and W. H. Kirchhoff, 1971, J. Mol. Spectrosc. 39, 136
and by
(3) A. P. Cox, S. D. Hubbard, and H. Kato, 1982, J. Mol. Spectrosc. 93, 196.
Pure rotational transitions obtained by FT-FIR spectroscopy were also used in the fit. The data set is described by
(4) D. McNaughton and D. N. Bruget, 1993, J. Mol. Spectrosc. 159, 340.
The transition frequencies have been kindly provided by the first author. These data were omitted for the second entry because of the more acurate data in (1).
Higher order distortion parameters were estimated based on H₂CS data, as detailed in (1), and were kept fixed in the fit. This entry is sufficiently accurate for all astronomical purposes. Transition frequencies with calculated uncertainties exceeding 0.2 MHz should be viewed with caution. R-branch transitions with uncertainties larger than 50 kHz have not been merged.
The dipole moment was assumed to agree with that of the main species, see e046509.cat.
At low temperatures, it may be necessary to discern between ortho-H₂C³⁴S and para-H₂C³⁴S. 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-H₂C³⁴S and para-H₂C³⁴S, respectively. The J_KaKc = 1₁₁ is the lowest ortho state. It is 10.2726 cm^–1 above ground.