The entry was substantially modified from the first entry dated Sep. 2000. Transition frequencies were reported by
(1) S. Yamamoto, S. Saito, M. Guélin, J. Cernicharo, H. Suzuki, and M. Ohishi, 1987, Astrophys. J. 323, L149.
Additional transition frequencies with hyperfine splitting were taken from
(2) A. L. Cooksy, C. A. Gottlieb, T. C. Killian, P. Thaddeus, N. A. Patel, K. H. Young, and M. C. McCarthy, 2015, Astrophys. J. Suppl. Ser. 216, Art. No. 30.
The parameter set is similar to that in (2). Uncertainties in (2) appeared to be conservative except for two lines with rather large residuals which were omitted. Transition frequencies with calculated uncertainties exceeding 0.2 MHz should be viewed with caution.
The vibrational energy was taken from
(3) F. J. Mazzotti, R. Raghunandan, A. M. Esmail, M. Tulej, and J. P. Maier, 2011, J. Chem. Phys. 134, Art. No. 164303;
Their origin assigned to a 2ν₇ band was interpreted as energy of the v₇ = 2⁰ substate.
The new dipole moment was assumed to be the same as in the X ²Σ⁺ ground vibrational state, see e049503.cat. This assumption may be reasonable.
The partition function of the main species takes into account all states presently available in the CDMS. It is converged fairly well up to about 150 K. Vibrational contributions to the partition function are also available. These should be viewed cautiously because of several estimates concerning vibrational energies.