A combined fit of several isotopic species and various vibrational states has been performed. Ground state lines of the main isotopolog were taken from
(1) S. K. Lee, H. Ozeki, and S. Saito, 1995, Astrophys. J. Suppl. Ser. 98, 351.
The stated uncertainties, with which the peak positions have been determined, are only a vague indication of the uncertainties of the transition frequencies, as is commonly found for data from that laboratory. With assumed uncertainties of 20 kHz for most of the lines, all but one line could be reproduced overall within the uncertainties. Excited state transitions were taken from
(2) J. R. Anacona, M. Bogey, P. B. Davies, C. Demuynck, J. L. Destombes, 1986, Mol. Phys. 59, 81.
Ground state transitions for the ³⁴S isotopolog were reported by
(3) F. J. Lovas, and R. D. Suenram, 1982, J. Mol. Spectrosc. 93, 416;
and by
(4) A. H. Saleck, H. Ozeki, and S. Saito, 1995, Chem. Phys. Lett. 244, 199.
One transition from (3) and two from (4) were omitted from the final fit. (4) also contained data for the ³³S and ¹⁵N isotopic species.
Infrared transitions were taken from
(5) A. Sinha, J. B. Burkholder, P. D. Hammer, C. J. Howard, 1988, J. Mol. Spectrosc. 130, 466.
A₀₀ and Y₂₀ were derived from data in
(6) A. Jenouvrier and B. Pascat, 1973, Can. J. Phys. 51, 2143.
The predictions should be reliable up to about 600 GHz, possibly higher. The partition function takes into account states up to v = 2; ground state values are given in parentheses.
The dipole moment was assumed to agree with that in the ground vibrational state, see e046515.cat.