A. Saha, Monali Kawade, H. Upadhyaya
Apr 18, 2013
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Journal
Chemical Physics
Abstract
Abstract The photodissociation dynamics of 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane) have been studied near 234 nm, in a molecular beam environment, employing resonance-enhanced multiphoton ionization with time-of-flight mass spectrometer (REMPI-TOF-MS). Both bromine and chlorine atoms are detected in both the ground and spin–orbit excited states. The C–Br bond scission is observed predominantly due to direct σ∗(C–Br) ← n(Br) transition, with translational energy distribution described with a soft impulsive model. The recoil anisotropy parameter (β) of 0.6 ± 0.2 for this channel vindicates the impulsive nature of dissociation. The diabatic crossing from the nσ∗(C–Br) surface to nσ∗(C–Cl) diabatic surface is responsible for chlorine formation via the C–Cl bond fission, which is supported by the excited state molecular orbital calculations. The velocity distribution of bromine atom has one component, however, that of chlorine atom is bimodal. Both fast and slow chlorine atom channels, with the β value of 0.3 ± 0.1, are produced impulsively from the nσ∗(C–Cl) repulsive surface.