The observed lines are from
(1) K. A. Walker and M. C. L. Gerry 1997, Chem. Phys. Lett. 278, 9;
and
(2) J. S. Robinson, A. J. Apponi, and L. M. Ziurys 1997, Chem. Phys. Lett. 278, 1.
The dipole moment is from an ab initio calculation by
(3) B. Ma, Y. Yamaguchi, and H. F. Schaefer, III 1995, Mol. Phys. 86, 1131.
Altered Dec. 2003: Since the number of strong hyperfine components is 18 for each rotational transition with large J and since the splitting is < 1 MHz for J = 6 – 5 (at 71813 MHz) and higher, predictions are given without hyperfine splitting. For low J transitions, predictions with hyperfine splitting are also available. NOTE: the partition function takes into account hyperfine splitting in all instances !