The data are based on a combined fit by
(1) H. S. P. Müller, 2023, unpublished.
Hyperfine-resolved transition frequencies in the ground vibrational state were reported by
(2) O. Asvany, C. R. Markus, A. Roucou, S. Schlemmer, S. Thorwirth, and C. Lauzin, 2021, J. Mol. Spectrosc. 378, Art. No. 111447.
Submillimeter data come from
(3) J. Cernicharo, S. Bailleux, E. Alekseev, A. Fuente, E. Roueff, M. Gerin, B. Tercero, S. P. Treviño-Morales, N. Marcelino, R. Bachiller, and B. Lefloch, 2014, Astrophys. J. 795, Art. No. 40.
We have attributed 20 kHz as uncertainties to these data in the present calculations. This may still be somewhat conservative. Infrared transition frequencies from
(4) W. C. Ho, I. Ozier, D. T. Cramb, and M. C. L. Gerry, 1991, J. Mol. Spectrosc. 149, 559;
and from
(5) M. López-Puertas, J.-M. Flaud, J. Peralta-Calvillo, B. Funke, and S. Gil-López, 2006, J. Mol. Spectrosc. 237, 218
were also used in the fit.
The calculations should be viewed with some caution for J > 25.
Quantum-chemical calculations of the dipole moments were taken from
(6) R. Polák and R. Fiser, 2004, Chem. Phys. 303, 73.
The spin-multiplicity of the ¹⁴N nucleus was considered in the calculation of the partition function. Contributions from the first excited vibrational state to the partition function were considered also, but are essentially negligible at 300 K.