Photodissociation of isomeric dichloroethylenes in the ultraviolet: effect of the second chlorine atom substitution on the dynamics

Abstract

We report the Cl^∗(²P_½) production dynamics in the near-UV dissociation of three isomers (cis-, gem-, and trans-) of dichloroethylene using the conventional resonance enhanced multiphoton ionization technique. Substantial amounts of Cl^∗ are produced in the wavelength range 222-304 nm. The Cl^∗ quantum yield (Φ^∗) is maximum at 304 nm for all the isomers Φ^∗_cis and is markedly higher than Φ^∗_gem and Φ^∗_transexcept at 222 nm. Existence of both direct and indirect dissociation pathways at these wavelengths complicates the Cl^∗ production dynamics. The higher value of Φ^∗_cis originates from a large contribution from direct dissociation via the (n, σ^∗) state.