Journal of Physical Chemistry A, Vol.108, No.50, 10973-10979, 2004
Recombination and reaction dynamics following photodissociation of CH3OCl in solution
We observe the dynamics of the products following the photodissociation of methyl hypochlorite (CH3OCl) at 267 nm in solution. An ultraviolet charge-transfer transition reveals the evolution of Cl atoms in carbon tetrachloride, dichloromethane, 1,4-dichlorobutane, and chlorocyclohexane, and the data suggest that Cl atoms rapidly form a complex with the solvent. The Cl atom signal decays in 300 ps or less as a result of diffusive geminate recombination and bimolecular reaction. Diffusive geminate recombination consumes roughly 30% to 60% of the fragments that initially escape the solvent cage, while the remaining Cl atoms either react with excess CH3OCl or abstract a hydrogen atom from the solvent. Reaction with CH3OCl plays a significant role in carbon tetrachloride, dichloromethane, and 1,4-dichlorobutane, where the hydrogen abstraction reaction is relatively slow, but the faster decay of C1 atoms in chlorocyclohexane is a result of hydrogen abstraction from the solvent. A weak absorption due to the rnethoxy radical in cyclohexane, where we cannot probe the Cl atom directly, also shows evidence of diffusive geminate recombination and hydrogen abstraction from the solvent.