C–Br bond fission dynamics in ultraviolet photodissociation of 1,2-dibromoethane

Abstract

The photodissociation of 1,2-dibromoethane was studied at 234 and 267 nm using velocity map imaging technique. The speed distributions for the Br( 2P 3/2) and Br ∗( 2P 1/2) were determined and mostly fitted by two Gaussian curves indicating different product channels. The direct C–Br bond fission dominates the process and the recoil anisotropies suggest a transition mainly parallel to the C–Br bond. Vibrational structures are shown with ∼550 cm −1 spacing originating from C–Br stretching excitation of C 2H 4Br photofragment. The three-body dissociation channel is also found. The total product quantum yields were Φ 234nm(Br ∗) = 0.14 and Φ 267 nm (Br ∗) = 0.17, respectively.