A line list was summarized by
(1) L. Zou, J.-C. Guillemin, R. A. Motiyenko, and L. Margulès, 2021, Astron. Astrophys. 649, Art. No. A60.
Most of the data are new measurements, frequently with partially resolved ¹⁴N hyperfine splitting. Additional microwave data are from
(2) I. N. Levine, 1962, J. Mol. Spectrosc. 8, 276;
and with higher resolution and greater accuracy from
(3) A. Klesing and D. H. Sutter, 1990, Z. Naturforsch. 45a, 817.
The mechanical parameters are almost the same as in (1). However, nuclear spin-rotation parameters were needed to fit the data from (3) reasonably well; these were already used in (3). Transitions with Δ(F) ≠ Δ(J) and J > 1 from this work were assigned larger uncertainties (5 kHz). Uncertainties in (1) were 2σ uncertainties and were adjusted accordingly. Two transition frequencies each with somewhat larger residuals were omitted from the data in (1) and in (3).
The calculations should be accurate enough for all observations. Frequencies with calculated uncertainties larger than 0.2 MHz should be viewed with caution.
¹⁴N hyperfine splitting may matter in astronomical observations. Therefore, a separate hyperfine calculation is provided for J ≤ 30 and K_a ≤ 10 below 500 GHz and with somewhat lowered intensity cut-offs. NOTE: The partition function takes into account the spin multiplicity of the ¹⁴N nucleus !
The dipole moment is from a quantum chemical calculation in (1). The b-component is in good agreement with the experimental value from (2), but the experimental a-component appears to be too large, whereas the calculated value is compatible with experimentally determined relative intensities in (1).