The photodissociation dynamics of 1,2-bromochloroethane (C2H4BrCl) was investigated near 234 nm. A two-dimen- sional photofragment ion-imaging technique coupled with a [2+1] resonance-enhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent Br(2P3/2) and Br*(2P1/2) atoms. The total trans- lational energy distributions for the Br and Br* channels were well characterized by Gaussian functions with average translational energies of 100 and 84 kJ/mol, respectively. The recoil anisotropies for the Br and Br* channels were measured to be β = 0.49 ± 0.05 for Br and 1.55 ± 0.05 for Br*. The relative quantum yield for Br* was found to be ΦBr* = 0.33 ± 0.03. The probability of nonadiabatic transition between A' states was estimated to be 0.46. The relevant nonadiabatic dynamics is discussed in terms of interaction between potential energy surfaces in Cs symmetry.
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