With respect to the Dec. 1999 entry, a combined fit of the v₂ = 0 and 1 data has been performed. Details of the fit have been published in
(1) H. S. P. Müller and S. Brünken, 2005, J. Mol. Spectrosc., 232, 213.
A considerable number of rotational transitions was taken from that work. Additional v₂ = 0, 1 transition frequencies were taken from the compilation of
(2) F. J. Lovas 1985, J. Phys. Chem. Ref. Data 14, 395; from
(3) S. C. Mehrotra, G. Bestmann, H. Dreizler, and H. Mäder, 1984, Z. Naturforsch. 39a, 633; from
(4) S. C. Mehrotra, H. Dreizler, and H. Mäder, 1984, Z. Naturforsch. 40a, 683; from
(5) P. A. Helminger and F. C. De Lucia 1985, J. Mol. Spectrosc. 111, 66; from
(6) E. A. Alekseev, S. F. Dyubko, V. V. Ilyushin, and S. V. Podnos 1996, J. Mol. Spectrosc. 176, 316; and from
(7) H. S. P. Müller, J. Farhoomand, E. A. Cohen, B. Brupbacher-Gatehouse, M. Schäfer, A. Bauder, and G. Winnewisser, 2000, J. Mol. Spectrosc., 201, 1.
Further v = 0 data were taken from
(8) S. P. Belov, M. Y. Tretyakov, I. N. Kozin, E. Klisch, G. Winnewisser, W. J. Lafferty, and J.-M. Flaud, 1998, J. Mol. Spectrosc. 191, 17.
The v₂ = 1 – 0 energy difference was determined by including ν₂ infrared transitions from
J.-M. Flaud, A. Perrin, L. M. Salah, and W. J. Lafferty, 1993, J. Mol. Spectrosc. 160, 272.
Transitions with uncertainties much larger than those at similar frequencies and with similar quantum numbers have not been merged.
Predicted uncertainties of the transition frequencies should be reliable up to about 3K"_a + J" ≈ 100.
The dipole moment is from
(10) D. Patel D. Margolese, and T. R. Dyke 1979, J. Chem. Phys. 70, 2740.
The partition function includes both vibrational states. The individual contributions (> 0) are given in parentheses.