2005ApJ...619..939G

The pure rotational spectra of the polar asymmetric top molecules S₃ and S₄have recently been observed in the laboratory for the first time. Approximately 150 transitions of S₃between 10 and 458 GHz and a similar number for S₄between 6 and 271 GHz have been measured. Many transitions of both molecules are accessible with existing telescopes across the entire radio band. The most interesting astronomical lines to 300 GHz are calculated here from the derived spectroscopic constants to an uncertainty of 1 km/s or better in equivalent radial velocity, and even at 700 GHz uncertainties are probably worse by only an order of magnitude. Both S₃and S₄are plausible candidates for detection in Galactic molecular sources, the atmosphere of the Jovian moon Io, and comets.