Rotational spectroscopy of HB33S:: The quadrupole coupling constant of 33S in thioborine

The unstable HBS molecule has been produced in the gas phase by a high-temperature reaction between crystalline boron and hydrogen sulfide. Ground state rotational spectra have been observed in the millimeter-wave region, from 75 to 460 GHz, for the previously unobserved (HBS)-B-11-S-33 and (HBS)-B-10-S-33 isotopic species. The analysis of the hyperfine structure produced by the B-10/11 and S-33 nuclear spins in the low-J rotational transitions has yielded the first evaluation of the quadrupole coupling constant of S-33 in the thioborine molecule, which was 6.361(15) MHz in (HBS)-B-11-S-33 and 6.329(17) MHz in (HBS)-B-10-S-33. In addition, further measurements have been performed for the most abundant isotopomers (HBS)-B-10/11-S-32/34, for which improved values of rotational, centrifugal, and hyperfine structure constants have been determined. (C) 2002 Elsevier Science (USA).