Optical-Optical Double Resonance Study of the $\acute{a}(^{3}A_{2})$ and $B(^{1}A_{1})$ States of Thiophosgene

Abstract

The $(^{3}A_{2})$ and $B(^{1}A_{1})$ states of jet-cooled thiophosgene $(Cl_{2}CS)$ have been studied by optical-optical double resonance (OODR) spectroscopy. Two OODR schemes have been used to probe the $B(^{1}A_{1})$ state. One scheme uses selected vibronic levels of the $A(^{1}A_{2})$ state as the intermediate state, while the other uses the vibrationless level of the $5(^{3}A_{2})$ state. All of the vibronic levels in the $33980-35600 cm^{-1}$ region can be rationalized with the following *** hand and fundamentals: $0^{0} = 34277 cm^{-1}, \nu_{1} = 505 cm^{-1}, \nu_{2} = 470 cm^{-1}, \nu_{3} = 213 cm^{-1}, \nu_{6} = 249 cm^{-1}, 42 = 341 cm^{-1}, 44 = 627 cm^{-1}.$ The discrepancies among the various studies of the $B(^{1}A_{1})$ state will be discussed and reconciled. The $\overline{a}(^{3}A_{2})$ state has been studied by a novel OODR scheme which uses the fluorescent vibrationless level of the $B(^{1}A_{1})$ state to monitor $\overline{a}(^{3}A_{2})-X(^{1}A_{1})$ transitions. A vibronic analysis has been carried out and the following origin band and fundamentals derived for the $\overline{a}(^{3}A_{2})$ state: $0^{0} = 17499 cm^{-1}, \nu_{1} = 923 cm^{-1}, \nu_{2} = 474 cm^{-1}, \nu_{3} = 247 cm^{-1}, 42 = 297 cm^{-1}, 44 = 560 cm^{-1}, 46 = 741 cm^{-1}$. The results will be compared with those from previous studies. The molecular structures in the $\overline{a}(^{3}A_{2})$ and $B(^{1}A_{1})$ states will be discussed. It is suggested that the wavenumber of $\nu_{6}$ in the $A(^{1}A_{2})$ state is $279 cm^{-1}$ instead of $189 cm^{-1}$.