The experimental lines are from
(1) B. Bak, O. J. Nielsen, H. Svanholt, A. Holm, N. H. Tourbro, A. Krantz, and J. Laureni, 1979, Acta Chem. Scand. A 33, 161.
Some higher order centrifugal distortion constants were estimated by
(2) H. S. P. Müller, 2022, unpublished.
Calculations of transition frequencies with K_a = 0 and 1 may be reliable into the 3 mm range. Transition frequencies with K_a larger than 1 should be viewed with increasing caution. The calculation were limited to K_a = 5.
At low temperatures, it may be necessary to discern between ortho-H₂CC³⁴S and para-H₂CC³⁴S. 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-H₂CC³⁴S and para-H₂CC³⁴S, respectively. The J_KaKc = 1₁₁ level is the lowest ortho level. It is 9.7357 cm^–1 above ground.
The dipole moment of the main isotopolog was determined by
(3) M. Winnewisser and E. Schäfer, 1980, Z. Naturforsch. A 35, 483.