title: A laser spectroscopic study of the X2pi(g), A2pi(u), and B2sigma+ states of BS2: Renner-Teller, spin-orbit, and K-resonance effects.
abstract: 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 0(0)0 and 2(1)1 bands of the A2pi(u)-X2pi(g) electronic transition in the visible. The A-X 2(1)1 and B2sigma(u)(+)-X2pi(g) 2(1) bands of jet-cooled BS2 were also studied with laser-induced fluorescence techniques. By fitting the 0(0) bands of both electronic transitions simultaneously, we were able to precisely determine the spin-orbit splittings in both the A and X states. Similarly, the 21 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 A state bending level shows small but definite K-resonance effects, which were fitted using a full matrix for the four components of upsilon2' = 1. The resulting parameters were used along with previously published data to refine the Renner-Teller analyses in both the A2pi(u), and X2pi(g) electronic states. Where possible, the fitted constants and observed boron isotope splittings have been shown to be in accord with theoretical estimates of their sign and magnitude.
authors.affiliation: Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA.
authors.forename: Sheng-Gui
authors.initials: SG
authors.lastname: He
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Clouthier
authors.forename: Allan G
authors.initials: AG
authors.lastname: Adam
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Tokaryk