Please note: With respect to the initial entry of Nov. 2004, values of Q and g_up were adjusted to be compatible with the 2nd ground state entry. The version number has been retained.
Frequencies without hyperfine splitting have been reported in
(1) M. Hutchinson, H. W. Kroto, and D. R. M. Walton, 1980, J. Mol. Spectrosc. 82, 394 and, more extensively, in
(2) K. M. T. Yamada, C. Degli Esposti, P. Botschwina, P. Förster, L. Bizzocchi, S. Thorwirth, and G. Winnewisser, 2004, Astron. Astrophys. 425, 767.
Transitions involving ¹⁴N hyperfine splitting were reported in
(3) M. E. Sanz, M. C. McCarthy, and P. Thaddeus, 2005, J. Chem. Phys. 122, Art. No. 194319.
¹⁴N hyperfine splitting may be resolved at low values of J. However, these transitions are expected to be too weak to be observable in the ISM/CSM.
The calculation should be reliable throughout.
The partition function DOES take into account now the hyperfine splitting, but no vibrational contributions !
Vibrational correction factors for a posteriori corrections have been derived for the main isotopolog in the harmonic approximation.
The vibrational energy is from a quantum-chemical calculation in (2). The dipole moment was assumed to be the same as that of the ground vibrational state, see e075503.cat.