The mechanism of photodissociation of CH₂＝CClF  ^hν >•CH＝CClF＋H and its following reactions have been investigated using the unrestricted Hartree-Fock (UHF), CI-Singles (CIS) and Complete Active Space Multiconfiguration SCF (CASSCF) methods with the aug-cc-pvdz basis set. The results show that the elimination of H atom on the same side of Cl atom occurs at the π→σ^*_C—H excited state when the molecule absorbs a photon. This finding has been further supported by the calculations of the electron transition using CIS method and by one electron density at Frank-Condon point using CASSCF methods, respectively. C-Cl and C-F bond fission reactions from the photodissociation product •CH＝CClF were also found.

Key words: 1-chloro-1-fluoroethylene, Frank-Condon point, CI-Singles, Complete Active Space Multiconfiguration SCF