The first entry from May 2006 has been revised considerably. Additional infrared data involving states v₂ = 2 and 3 as well as v₃ = 1 and v₁ = 1 were included along with additional pure rotational data pertaining to v₂ = 2 and 3.
Data for v = 0 and v₂ = 1, including direct-l-type transitions up to J = 35 for v₂ = 1, were reported in
(1) U. Fuchs, S. Brünken, G. W. Fuchs, S. Thorwirth, V. Ahrens, F. Lewen, S. Urban, T. Giesen, and G. Winnewisser, 2004, Z. Naturforsch. 59a, 861.
Additional v = 0 data come from
(2) G. Cazzoli and C. Puzzarini, 2005, J. Mol. Spectrosc. 233, 280;
and from
(3) F. Maiwald, F. Lewen, V. Ahrens, M. Beaky, R. Gendriesch, A. N. Koroliev, A. A. Negirev, D. G. Paveljev, B. Vohwinkel, and G. Winnewisser 2000, J. Mol. Spectrosc. 202, 166.
Further direct-l-type transitions 6 ≤ J ≤ 15 were published in
(4) M. Winnewisser and J. Vogt, 1978, Z. Naturforsch. 33a, 1323.
The 2nd entry also employs v₂ = 2 and 3 rotational data from
(5) J. Preusser and A. G. Maki, 1993, J. Mol. Spectrosc. 162, 484.
The fit also takes into account the very extensive infrared data between the various vibrational states from
(6) A. G. Maki, G. C. Mellau, S. Klee, M. Winnewisser, and W. Quapp, 2000, J. Mol. Spectrosc. 202, 67.
The main improvement occured in the partition function, which is essentially converged at 300 K and probably still good up to about 500 K. The rotational part is well converged up to 1000 K. The frequencies are also better at higher values of J. Predictions above J = 60 and 66 should be viewed with some caution for direct-l-type and regular rotational transitions, respectively.
The dipole moment was assumed to be the same as for the main isotopic species; see e027503.cat.
Note: the spin multiplicity g_I of 3 for the ¹⁴N nucleus has been considered in the calculation of the partition function and the upper state degeneracy g_up.
The partition function takes into account all vibrational states used in the fit.