The rotational lines have been reported by
(1) R. K. Bauer and H. Lew, 1963, Can. J. Phys. 41, 1461; and by
(2) S. E. Veazey and W. Gordy, 1965, Phys. Rev. 138A, 1303.
The data reported and used in the fit extend to v = 2. Hyperfine effects due to the ²³Na nucleus, reported in (1), have been subtracted off. They were not considered in the predictions because of their small effects even at very low values of J.
Rovibrational transitions up to v = 4 – 3 have been also used in the fit. They were reported by
(3) A. Munteanu, B. Guo, and P. Bernath, 1996, J. Mol. Spectrosc. 176, 274.
Predictions of higher J transitions should be viewed with some caution.
The partition function takes into account all states up to v = 8. Contributions of vibrational states to the partition function are available.
The dipole moments were taken from
(4) G. Gräff and G. Werth, 1965, Z. Phys. 183, 223.