New low-J data, to a considerable part with resolved ¹⁴N and D hyperfine structure, have been employed with respect to the Nov. 2005 entry. The J" = 0 transition was taken from astronomical observations by
(1) F. F. S. van der Tak, H. S. P. Müller, M. E. Harding, and J. Gauss, 2009, Astron. Astrophys., accepted;
the J" = 0 to 2 transitions were taken from laboratory measurements by
(2) H. A. Bechtel, A. H. Steeves, and R. W. Field, 2006, Astron. Astrophys. 649, L53;
the J" = 3 transition was taken from
(3) T. Okabayashi and M. Tanimoto, 1993, J. Chem. Phys. 99, 3268;
the remaining transitions up to 2 THz were published by
(4) S. Brünken, H. S. P. Müller, S. Thorwirth, F. Lewen, and G. Winnewisser, 2006, J. Mol. Struct. 380–381, 3.
The predictions should be reliable up to at least 2.5 THz.
At low J, the ¹⁴N and D hyperfine splitting has been resolved in astronomical observations. Therefore, a separate hyperfine calculation up to J" = 2 is provided along with appropriate partition function values. The dipole moment was assumed to agree with that of HNC, see e027502.cat.