A global fit of data for all isotopic species and the experimental lines have been summarized in
(1) H. S. P. Müller, M. C. McCarthy, L. Bizzocchi, H. Gupta, S. Esser, H. Lichau, M. Caris, F. Lewen, J. Hahn, C. Degli Esposti, S. Schlemmer, and P. Thaddeus, 2007, Chem. Phys. Phys. Chem., 9, 1579.
The newly recorded transitions extend to almost 1 THz and to high vibrational states. Previous pure rotational data from
(2) E. Tiemann, E. Renwanz, J. Hoeft, and T. Törring, 1972, Z. Naturforsch. 27a, 1566;
and from
(3) M. E. Sanz, M. C. McCarthy, and P. Thaddeus, 2003, J. Chem. Phys., 119, 11715; as well as rovibrational data from
(4) C. I. Frum, R. Engleman, Jr., and P. F. Bernath, 1990, J. Chem. Phys., 93, 5457;
and from
(5) H. Birk and H. Jones, 1972, Chem. Phys. Lett. 175, 536
were also used in the fit.
The predictions should be adequate up to about 2 THz.
The dipole moment was assumed to agree with that of the main species, see e060506.cat.
Vibrational states v ≤ 10 have been considered for the calculation of the partition function. Contributions of the individual vibrations are given in parentheses for v = 0, 1.
Note: the ²⁹Si hyperfine splitting of about 21 and 14 kHz for J" = 0 and 1, respectively, has been resolved in the laboratory. As SiS does not occur in cold sources it is unlikely that this splitting will be resolved in astronomical observations. The partition function does not take into account this splitting.