15min:

DENNIS J. CLOUTHIER AND SHENG-GUI HE, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; ALLAN G. ADAM AND DENNIS W. TOKARYK, Departments of Chemistry and Physics, and the Centre for Laser, Atomic, and Molecular Sciences, University of New Brunswick, Fredericton, NB, Canada, E3B 6E2.

The lowest-lying vibronic levels of the X, A, and B states of BS₂ have been investigated at high resolution using a combination of room-temperature absorption and supersonic jet data. In both cases, the BS₂ radical was prepared in an electric discharge using a precursor gas mixture of BCl₃, CS₂, and either helium or argon. Extensive absorption spectra were obtained for the 0₀⁰ and 2₁¹ bands of the A² _u - X² _g electronic transition in the visible using a mutipass discharge cell and a scanning ring dye laser. The A- X and B- X 2₁¹ bands of jet-cooled BS₂ were also studied with laser-induced fluorescence techniques. By fitting the 0₀⁰ bands of both electronic transitions simultaneously, we were able to precisely determine the spin-orbit splittings in both the A and states. The 2₁¹ bands were fitted in a merged analysis in order to determine the relative separations of the vibronic components of the ground and first excited state bending levels as accurately as possible. Due to a large spin-orbit splitting and small Renner-Teller interaction, the state bending level shows small but definite K-resonance effects, which were fitted using a full matrix for the four components of v₂ = 1. The resulting parameters were used along with previously published data to refine the Renner-Teller analyses in both the A² _u and X² _g electronic states.