CDMS

Methyl mercaptan a threefold internal rotor and the sulfur analog of methanol, has been (CH3SH), detected in the interstellar medium. The extry is based on (1) L.-H. Xu, R. M. Lees, G. T. Crabbe, J. A. Myshrall, H. S. P. Müller, C. P. Endres, O. Baum, F. Lewen, S. Schlemmer, K. M. Menten, and B. E. Billinghurst, 2012, J. Chem. Phys. 137, Art. No. 104313. Extensive b-type transition frequencies were determined in that work between about 1.1 and 1.5 THz as welltogether with previously reported data from as from broad FTFIR spectra. The data were fit (2) F. L. Bettens, K. V. L. N. Sastry, E. Herbst, S. Albert, L. C. Oesterling, and F. C. De Lucia, 1999, Astrophys. J. 510, 789; from (3) K. V. L. N. Sastry, E. Herbst, R. A. Booker, and F. C. De Lucia, 1986, J. Mol. Spectrosc. 116, 120; and from (4) R. M. Lees and M. A. Mohammadi, 1980, Can. J. Phys. 58, 1640.
The predictions extend to J := 40, K_a := 20, and v_t := 2. Predictions have been truncated at 1 THz. Transitions with predicted uncertainties larger than 0.5 MHz should be viewed with some caution, those with uncertainties larger than 5 MHz should be great caution.
State numbers 0, 3, and 6 refer to lines with A symmetry with v_t = 0, 1, and 2; state numbers 1, 4, and 7 refer to lines with E symmetry with K_a ≤ 0 and with v_t = 0, 1, and 2; state numbers 2, 5, and 8 refer to lines with E symmetry with K_a > 0 and with v_t = 0, 1, and 2.
Lower state energies are given referenced to the J = K = 0, A, v_t = 0 level, which is about 112 cm^–1 above the bottom of the torsional potential well.
The partition function consider states with v_t ≤ 3, J ≤ 44, and K ≤ 20. The truncation error is below 1 % up to about 200 K. It exceeds 10 % at about 300 K.
Experimental microwave and millimeter-wave transition frequencies have not been merged.
The experimental ground state dipole moment was reported in (5) S. Tsunekawa, I. Taniguchi, A. Tambo, T. Nagai, and T. Kojima, 1989, J. Mol. Spectrosc. 134, 63.