Note: This version is considered to be the only one as of Nov. 2014 because of new laboratory measurements. Version 3 is still available in the archive. The frequencies in version 3 are too low by a few kilohertz at low values of J. The differences can be important for investigations of cold molecular clouds.
Similar rest frequency issues may exist for N₂D⁺, tag 030509.
(1) G. Cazzoli, L. Cludi, G. Buffa, and C. Puzzarini, 2012, Astrophys. J. Suppl. Ser. 203, Art. No. 11
reported the transitions with hyperfine splitting up to J = 4 – 3 near 373 GHz. In addition, they reported transition frequencies between 1.0 and 1.6 GHz.
(2) T. Amano, T. Hirao, and J. Takano, 2005, J. Mol. Spectrosc. 234, 170
reported frequencies for the transitions with J" = 4 to 7. The uncertainties of 30 kHz appeared to be too conservative and were modified to 10 kHz.
Further transition frequencies above 800 GHz were taken from
(3) P. Verhoeve, E. Zwart, M. Versluis, M. Drabbles, J. J. ter Meulen, W. L. Meerts, A. Dymanus, and D. B. McLay, 1990, Rev. Sci. Instrum. 61, 1612.
The predictions are deemed to be sufficiently accurate for all radio astronomical observations. The experimental data likely cover the range nedded by astronomers. The predictions should be reliable up to at least 2.5 THz.
Additional hyperfine splitting was taken from astronomical observations by
(4) P. Caselli, P. C. Myers, and P. Thaddeus, 1995, Astrophys. J. 455, L77.
A separate hyperfine calculation is provided for J" ≤ 9. Transitions with experimental uncertainties > 100 kHz have not been merged.
Note: The partition function takes into account the ¹⁴N hyperfine splitting as well as contributions from the vibrationally excited v₂ = 1 state ! Individual non-zero contributions are given in parentheses.
The dipole moment was reported by
(5) M. Havenith, E. Zwart, W. L. Meerts, J. J. ter Meulen, 1990, J. Chem. Phys. 93, 8446.