The present entry was greatly extended in J and K quantum numbers as well as in frequency with respect to the first entry from Jan. 2012. The extry is based on
(1) O. Zakharenko, V. V. Ilyushin, F. Lewen, H. S. P. Müller, S. Schlemmer, E. A. Alekseev, M. L. Pogrebnyak, I. A. Armieieva, O. Dorovskaya, L.-H. Xu, and R. M. Lees, 2019, Astron. Astrophys. 629, Art. No. A73.
New measurements covering almost all of the region between 49 and 510 GHz replace a large fraction of the older literature data and supplements it with new assignments. Large portions of the data between about 1.1 and 1.5 THz and near 1.8 THz from
(2) L.-H. Xu, R. M. Lees, G. T. Crabbe, J. A. Myshrall, H. S. P. Müller, C. P. Endres, O. Baum, F. Lewen, S. Schlemmer, K. M. Menten, and B. E. Billinghurst, 2012, J. Chem. Phys. 137, Art. No. 104313
were reanalyzed. A small part of the data and the extensive FTFIR data were taken directly from that work. Data below 49 GHz were taken from
(3) T. Kojima and T. Nishikawa, 1957, J. Phys. Soc. Jpn. 12, 680;
and from
(4) T. Kojima, 1960, J. Phys. Soc. Jpn. 15, 1284;
and from
(5) R. M. Lees and M. A. Mohammadi, 1980, Can. J. Phys. 58, 1640.
Two lines near 83 GHz were also taken from (5). Data between 150 and 154 GHz, near 190.2 GHz, between 251 and 260 GHz, and near 326.7 GHz were taken mostly from
(6) K. V. L. N. Sastry, E. Herbst, R. A. Booker, and F. C. De Lucia, 1986, J. Mol. Spectrosc. 116, 120;
and from
(7) F. L. Bettens, K. V. L. N. Sastry, E. Herbst, S. Albert, L. C. Oesterling, and F. C. De Lucia, 1999, Astrophys. J. 510, 789.
Experimental microwave and millimeter-wave transition frequencies have not been merged. The list with reference labels can be accessed in the Cologne Spectroscopy Data section.
The calculated frequencies should be reliable throughout.
Please note that the vibrational identifiers correspond in the present calculation to the torsional quantum number m. The values 0 and 1 correspond to A and E symmetry lines, respectively, of v_t = 0. The corresponding values for v_t = 1 are –3 and –2, those for v_t = 2 are 3 and 4. The signs of K_a designate the parity for A symmetry lines; for E symmetry lines, they designate in the picture of a degenerate state of a symmetric rotor.
Lower state energies are given referenced to the J = K = 0, A, v_t = 0 level, which is about 112 cm^–1 above the bottom of the torsional potential well.
Please note that the upper state degeneracy and the partition function values were calculated here with g_I = 1, not 4 as in the earlier compilation. The partition function consider states with v_t ≤ 2, J ≤ 70, and K ≤ 20.
The experimental ground state dipole moment was reported in
(6) S. Tsunekawa, I. Taniguchi, A. Tambo, T. Nagai, and T. Kojima, 1989, J. Mol. Spectrosc. 134, 63.