Photodissociation of CH 2BrCl at 248 and 193 nm investigated by translational spectroscopy

Abstract

The photodissociation of CH 2BrCl at 248 and 193 nm has been studied by translational spectroscopy. Both the product translational energy distribution and the anisotropy parameter were derived from the measured time-of-flight spectra. Results show that at 248 nm, CH 2BrCl exclusively dissociates to CH 2Cl+Br with average translational energy of 20 kcal/mol. On absorption of 193 nm photons, two different paths, (1) CH 2BrCl→CH 2Cl+Br and (2) CH 2BrCl→CH 2Br+Cl, were detected with average translational energies of 32 and 24 kcal/mol, respectively. The branching ratio of reactions (1)/(2) was deduced as −4.5. From the measured values of product anisotropy parameter at these two wavelengths, we conclude that reaction (1) occurs rapidly after excitation via an A′←A′ transition.