The rotational lines were summarized by
(1) M. Caris, F. Lewen, H. S. P. Müller, and G. Winnewisser, 2004, J. Mol. Struct. 695–696, 243.
The predictions are based on a combined fit of all isotopic species from (1). Vibrational energies were derived from Y_i0 values taken from
(2) E. J. Barton, C. Chiu, S. Golpayegani, S. N. Yurchenko, J. Tennyson, D. J. Frohman, and P. F. Bernath, 2014, Mon. Not. R. Astron. Soc. 442, 1821.
In addition, three higher order parameters were estimated from various trial fits based on the data from (1). The predictions extend to v = 5 and up to 1.9 THz.
Predictions should be viewed with caution for transitions with calculated uncertainties above 0.2 MHz. Hyperfine effects due to the ⁴⁰K and ³⁵Cl nuclei were not considered in the predictions because of their small effects even at very low values of J.
The dipole moments were calculated from the formula below derived by mass scaling from
(3) R. van Wachem and A. Dymanus, 1967, J. Chem. Phys. 46, 3749.