Fourier transform microwave transitions with ¹⁴N and D hyperfine splitting was published in
(1) Y. Hirahara, Y. Ohshima, Y. Endo, 1993, Astrophys. J. 403, L83.
Two additional lower J transition frequencies were taken from astronomical observations by
(2) J. Cernicharo, B. Tercero, C. Cabezas, M. Agúndez, E. Roueff, R. Fuentetaja, N. Marcelino, and P. de Vicente, 2024, Astron. Astrophys. 682, L13.
The D value was estimated.
The calculation may be accurate enough throughout; some caution, however, is advised.
¹⁴N and possibly D hyperfine splitting matter in some astronomical observations. Therefore, a separate hyperfine calculation is provided for J' ≤ 5 below 45 GHz. NOTE: The partition function does take into account the spin multiplicity of the ¹⁴N and D nuclei !
The dipole moment of the main isotopolog is from a quantum chemical calculation by
(3) P. Botschwina, M. Horn, S. Seeger, and J. Flügge, 1992, Chem. Phys. Lett. 195, 427.