The experimental laboratory frequencies were summarized in
(1) M. Bogey, C. Demuynck, J. L. Destombes, Y. Vallee, and J. L. Ripoll, 1995, J. Mol. Spectrosc. 172, 344.
The total dipole moment was taken from an ab initio calculation published in
(2) A. Császár, 1989, Chem. Phys. Lett. 162, 361.
The ratio of the a- and b-dipole moment components was determined in (1) from relative intensity measurements.
The ¹⁴N hyperfine splitting may be resolvable at lower frequencies or at lower quantum numbers. Therefore, a separate calculation with hyperfine structure is available up to 300 GHz and with J´ up to 25. In the general entry, the spin-multiplicity of the ¹⁴N nucleuis was not considered in the calculation of the partition function. However, values in parentheses do include it.
Predictions of transitions with very high quantum numbers or at rather high frequencies should be viewed with caution. Transition frequencies with predicted uncertainties of less than 1 MHz should be reliable.