The first entry from June 2006 was reevaluated considerably because of additional millimeter and submillimeter data. The initial transition frequencies were taken from
(1) M. Rodler, R. D. Brown, P. D. Godfrey, and L. M. Tack, 1984, Chem. Phys. Lett. 110, 447;
and from
(2) M. Rodler, R. D. Brown, P. D. Godfrey, and B. Kleibömer, 1986, J. Mol. Spectrosc. 118, 267.
New millimeter and submillimeter data were taken from
(3) C. Degli Esposti, L. Dore, and L. Bizzocchi, 2014, Astron. Astrophys. 565, Art. No A66.
Two of the three K_a = 2 – 1 rotational transitions in (1) and (2) turned out to be misassigned, causing substantial changes in part. The weak a-type transitions were truncated after K_a = 7 because of the onset of a perturbation that is only described moderately well. NOTE: The present entry provides ¹⁴N hyperfine splitting and the very small tunneling splitting throughout because the molecule is more likely associated with cold sources rather than warm ones. The calculations are sufficiently accurate for observations of cold sources and should also be accurate enough for observation of warmer sources. Transition frequencies with calculated uncertainties exceeding 0.1 MHz should be viewed with caution.
The dipole moment was reported in (1).