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

We report the Cl∗(2P1/2) 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 and ϕ cis ∗ is markedly higher than ϕ gem ∗ and ϕ trans ∗ except 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.