LASER SPECTROSCOPY OF THE $\tilde{X}^2\Pi_g$, $\tilde{A}^2\Pi_u$ AND $\tilde{B}^2\Sigma_u^+$ STATES OF BS$_2$: RENNER-TELLER, SPIN-ORBIT and $K$-RESONANCE EFFECTS
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Date
2005
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Publisher
Ohio State University
Abstract
The lowest-lying vibronic levels of the $\tilde{X}$, $\tilde{A}$, and $\tilde{B}$ states of BS$_2$ have been investigated at high resolution using a combination of room-temperature absorption and supersonic jet data. In both cases, the BS$_2$ radical was prepared in an electric discharge using a precursor gas mixture of BCl$_3$, CS$_2$, and either helium or argon. Extensive absorption spectra were obtained for the $0_0^0$ and $2_1^1$ bands of the $\tilde{A}^2\Pi_u - \tilde{X}^2 \Pi_g$ electronic transition in the visible using a mutipass discharge cell and a scanning ring dye laser. The $\tilde{A}- \tilde{X}$ and $\tilde{B}- \tilde{X}$ $2_1^1$ bands of jet-cooled BS$_2$ were also studied with laser-induced fluorescence techniques. By fitting the $0_0^0$ bands of both electronic transitions simultaneously, we were able to precisely determine the spin-orbit splittings in both the $\tilde{A}$ and $\tilde {X}$ states. The $2_1^1$ 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 $\tilde {A}$ state bending level shows small but definite $K$-resonance effects, which were fitted using a full matrix for the four components of $v_2 = 1$. The resulting parameters were used along with previously published data to refine the Renner-Teller analyses in both the $\tilde{A}^2\Pi_u$ and $\tilde{X}^2\Pi_g$ electronic states.
Description
Author Institution: Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; Departments of Chemistry and Physics, and the Centre for Laser, Atomic, and Molecular Sciences, University of; New Brunswick, Fredericton, NB, Canada, E3B 6E2