ABINITIO CI STUDY OF THE LASER-RADIATION EFFECT ON PYROLYSIS OF 1,2-DICHLOROETHANE

Electronic spectra of 1,2-dichlorethane and the 1,2-dichloroethyl radical have been calculated with ab initio CI methods in order to propose a theoretical interpretation for the well known effect of laser radiation on the pyrolysis of 1,2-dichloroethane. According to this work, the 1,2-dichloroethyl radical produced by thermal pyrolysis is the most probable candidate for the absorption of 308 nm laser radiation used in experimental studies. Consequently, we also present a theoretical study of the C-Cl bond breaking process in the first excited state of the 1,2-dichloroethyl radical, leading to the formation of vinyl chloride and atomic chlorine. No potential barrier appears along the calculated dissociation pathway. Moreover the broad energy excess of the products formed enable us to propose an interpretation for the beneficial effect of laser radiation on the pyrolysis of 1,2-dichloroethane.