The entry was reevaluated with respect to the second entry from Oct. 2004 as described in
(1) T. F. Giesen, M. E. Harding, J. Gauss, J.-U. Grabow, and H. S. P. Müller, 2020, J. Mol. Spectrosc. 371, Art. No. 111303.
Transition frequencies with ¹⁴N hyperfine splitting were taken from that work and from
(2) M. C. McCarthy, E. S. Levine, A. J. Apponi, and P. Thaddeus, 2000, J. Mol. Spectrosc. 203, 75.
Additional frequencies without hyperfine splitting were published by
(3) C. Kirby, H. W. Kroto, and D. R. M. Walton, 1980, J. Mol. Spectrosc. 83, 261.
A large body of millimeter wave data was taken from
(3) L. Bizzocchi and C. Degli Esposti; 2004, Astrophys. J. 614, 518.
The hyperfine splitting should be described better in the present entry and the hyperfine free transition frequencies are slightly more certain. The calculations should be accurate enough for all observational purposes.
The ¹⁴N hyperfine splitting may be resolved in the ISM at low values of J. Therefore, separate calculations with ¹⁴N hyperfine splitting are available for J" < 20. NOTE: The partition function DOES take into account now the hyperfine splitting, but no vibrational contributions !
Information on vibrational contributions to the partition function are also available.
The dipole moment is from an ab initio calculation by
(4) P. Botschwina, M. Horn, K. Markey, and R. Oswald, 1997, Mol. Phys. 92, 381.