The entry was reevaluated with respect to the first entry from Oct. 2004/June 2001. The experimental lines are still entirely from
(1) M. C. McCarthy, E. S. Levine, A. J. Apponi, and P. Thaddeus, 2000, J. Mol. Spectrosc. 203, 75.
The conservative uncertainties were reduced by a factor of 2. The calculated frequencies should be viewed with some caution above 40 GHz. The ¹⁴N hyperfine splitting has been resolved in the laboratory for J" = 9 – 14. The observed splittings are very small and the value for eQq too large. Values for eQq and C were evaluated for this entry upon comparison with experimental and quantum chemically derived values of other HC_xN molecules presented in
(2) T. F. Giesen, M. E. Harding, J. Gauss, J.-U. Grabow, and H. S. P. Müller, 2020, J. Mol. Spectrosc. 371, Art. No. 111303.
The ¹⁴N hyperfine splitting may be resolved in the ISM at low values of J. Therefore, separate calculations with ¹⁴N hyperfine splitting are available for J" < 20. NOTE: The partition function DOES take into account now the hyperfine splitting, but no vibrational contributions !
The dipole moment is from an ab initio calculation by
(3) P. Botschwina and M. Horn, 1997, J. Mol. Spectrosc. 185, 191.