15min:

K. IZUMI, K. KAWAGUCHI, Department of Chemistry, Okayama University, Okayama, Japan, 700-8530; E. A. COHEN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109-8099; K. D. SETZER AND E. H. FINK, Physikalische Chemie-Fachbereich C, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany.

The millimeterwave rotational spectrum of BiS in its X ₁~² _1/2 state was observed in the frequency range of 150-300 GHz. BiS was produced in a high-temperature oven by a discharge in a mixture of Bi vapor and CS2. A White-type multipath cell was used to enhance the absorption pathlength. Near infrared bands of the transition were measured by Fourier-transform emission spectroscopy in the 6400-7400 cm^-1 region, where BiS was produced by reaction of bismuth and sulfur vapor and excited by collisional energy transfer from the metastable a¹ _g electronic state of O₂. A simultaneous analysis of millimeterwave and FT data was carried out to give rotational, fine and hyperfine constants for the X ₁~² _1/2 and X ₂~² _3/2 states. Ninety seven rotational J=1 features from J'=23.5 to 41.5 and 545 NIR features representing assignments of a wide range of J's were included in the fit. The hyperfine parameters are consistent with those of BiO with slightly less unpaired electron density in the antibonding orbital on the Bi atom. Examples of the spectra will be shown. The fitting procedure with spcat and the resulting parameters will be discussed.