The experimental lines are from
(1) F. C. De Lucia and J. W. Cederberg, 1971, J. Mol. Spectrosc. 40, 52,
and from
(2) R. L. Cook, F. C. De Lucia, and P. Helminger, 1972, J. Mol. Spectrosc. 41, 123.
The latter work also contains some data from
(3) C. A. Burrus, unpublished.
Also included in the fit are far-infrared transitions from
(4) C. Camy-Peyret, J.-M. Flaud, L. Lechuga-Fossat, and J. W. C. Johns, 1985, J. Mol. Spectrosc. 109, 300;
and one TuFIR transition from
(5) R. Gendriesch, unpublished.
Transition frequencies from (1) and (2) have 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-D₂S and para-D₂S. The ortho and para states are described by K_a + K_c being even and odd, respectively. The nuclear spin-weights are 2 and 1 for ortho-D₂S and para-D₂S, respectively. The J_KaKc = 1₀₁ is the lowest para state. It is 6.9561 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 2 for the separate ortho predictions has been eliminated.
The dipole moment is from
(6) R. Viswanathan and T. R. Dyke, 1984, J. Mol. Spectrosc. 103, 231.