The observed transitions were taken from
(1) E. F. Pearson and M. B. Trueblood, 1973, Astrophys. J. 179, L145;
from
(2) P. Kuipers, T. Törring, and A. Dymanus, 1976, Chem. Phys. 15, 457;
and from
(3) Y. Kawashima, R. D. Suenram, and E. Hirota, 1996, J. Mol. Spectrosc. 175, 99.
The predictions should be reliable up to 600 GHz.
At low values of J, ²³Na hyperfine splitting is resolvable. Therefore, a separate prediction considering ²³Na hyperfine splitting with J" ≤ 4 is available. Note: The partition function does not include the spin-multiplicities of ²³Na ! Therefore, partition function values have to be multiplied by 4 when considering ²³Na hyperfine splitting !
The dipole moment was taken from (3).