Photodissociation dynamics of CH2BrCl at 234 nm

The photodissociation dynamics of CH2BrCl has been studied at 234 nm utilizing the molecular beam-imaging system. In the photolysis, the C-Br bond fission is observed exclusively. The internal energy of the Br(P-2(3/2)) channel consists of two parts which is caused by the interaction between sigma*(C-Br) and sigma*(C-Cl) surfaces. This separation is newly resolved and studied to unravel the effect of another chromophore. The energy separation of two peaks is 25 kJ mol(-1) and the ratio of fast to slow one is 3.2. The fast part is interpreted in terms of a rigid impulsive model with no vibrational excitation and the slow part by a soft one with a little vibrational excitation, respectively. The energy gap is suggested to be due to an umbrella motion. (C) 2000 Elsevier Science B.V. All rights reserved.