No rotational data are available at present for ³⁴SH⁺. The transition frequencies were evaluated from an isotopic invariant fit with data from version 4 of the main species. Because of the necessary neglect of parameters describing the breakdown of the Born-Oppenheimer approximation, predictions were limited to the N = 1 – 0 transition; these are likely the only transitions observable in astronomical sources. The position of each fine structure component is uncertain to 1 or 2 MHz, potentially more. The uncertainties of the hyperfine splittings within one fine structure component are approximately correct. Further details are given in
(1) S. Muller, H. S. P. Müller, J. H. Black, M. Gérin, F. Combes, S. Curran, E. Falgarone, M. Guélin, C. Henkel, S. Martín, K. M. Menten, E. Roueff, S. Aalto, A. Beelen, T. Wiklind, and M. A. Zwaan, 2017, Astron. Astrophys. 606, Art. No. A109.
New N = 1 – 0 transition frequencies, except one, were taken from
(2) D. T. Halfen and L. M. Ziurys, 2015, Astrophys. J. 814, Art. No. 119;
see (1) for details; the correct transition frequency was estimated there. Additional, albeit redundant and less accurate frequency information was taken from
(3) C. Savage, A. J. Apponi, and L. M. Ziurys, 2004, Astrophys. J. 608, L73;
and from
(4) H. S. P. Müller, J. R. Goicoechea, J. Cernicharo, M. Agúndez, J. Pety, S. Cuadrado, M. Gerin, G. Dumas, and E. Chapillon, 2014, Astron. Astrophys. 569, Art. No. L5.
In addition, extrapolated zero-field transition frequencies from
(5) J. M. Brown and H. S. P. Müller, 2009, J. Mol. Spectrosc. 255, 68
were used in the fit. These were derived from laser magnetic resonance measurements in
(6) D. C. Hovde and R. J. Saykally, 1987, J. Chem. Phys. 87, 4332.
Also used in the fit were infrared transition frequencies up to v = 2 – 1 and 4 – 3, respectively, from
(7) P. R. Brown, P. B. Davies, and S. A. Johnson, 1986, Chem. Phys. Lett. 132, 582;
and from
(8) S. Civiš, C. E. Blom, and P. Jensen, 1989, J. Mol. Spectrosc. 138, 69.
The dipole moment is assumed to agree with that of the main isotopolog, see e033505.cat.