According to quantum chemical calculations, thioxyhydroxymethylium is considerably higher in energy than its oxythiohydroxymethylium isomer. With respect to the first entry of Sep. 2011, millimeter and lower submillimeter data were determined by
(1) V. Lattanzi, M. Sanz-Novo, V. M. Rivilla, M. Araki, H. A. Bunn, J. Martín-Pintado, I. Jiménez-Serra, and P. Caselli, 2024, Astron. Astrophys. 689, Art. No. A260.
The transition frequencies were kindly communicated by the first author. Earlier microwave data from
(2) Y. Ohshima and Y. Endo, 1996, Chem. Phys. Lett. 256, 635
were also used in the fit. The A rotational parameter was kept fixed to the value from an infrared study by
(3) T. Nakanaga and T. Amano, 1987, Mol. Phys. 61, 313.
The parameter d₂ was kept fixed to an estimated value. The change with respect to the value used in (1) is almost negligible.
The calculation is sufficiently accurate for cold and luke-warm sources. Calculated frequencies with K_a = 2 or larger than 3 or with calculated uncertainties larger than 0.2 MHz should be viewed with caution for observations of warmer sources.
The dipole moment components are from a quantum chemical calculation by
(4) S. E. Wheeler, Y. Yamaguchi, and H. F. Schaefer III, 2006, J. Chem. Phys. 124, Art. No. 044322.
However, b-type transitions were not calculated as their positions are too uncertain.