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

The photodissociation of 1,2-dibromoethane was studied at 234 and 267 nm using velocity map imaging technique. The speed distributions for the Br(2P3/2) and Br∗(2P1/2) 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 C2H4Br photofragment. The three-body dissociation channel is also found. The total product quantum yields were Φ234nm(Br∗) = 0.14 and Φ267 nm(Br∗) = 0.17, respectively.