Photodissociation of bromine azide

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Abstract
Bromine azide was photodissociated by using excimer laser sources at 222 and 308 nm. The primary fragments produced are N2(A 3Σu+) and NBr(X 3Σ−), with some N2(B 3Πg) produced at 222 nm. In contrast to analogous experiments with ClN3, NBr(b 1Σ+) was not observed. From the formation of these products, it is concluded that the heat of formation of BrN3 is greater than 122 kcal/mol. The N2(A 3Σu+) produced by photodissociation decays by a combination of pseudo-first order and second order processes. The first order process is reaction with the parent BrN3, generating N2(B 3Πg) as a product. The rate constant for N2(A 3Σu+) quenching by BrN3 is 1.2±0.2×10−12 cm3 molecule−1 s−1. This first order process dominates for photolysis at 222 nm. The second order process involves reaction of N2(A 3Σu+) with another photodissociation fragment, and produces intense emission in the vicinity of 292 nm. This emission has been tentatively identified as the D′(3 Π2g) → A′(3 Π2u) transition in Br2. The second order process is much more important in the decay of N2(A 3Σu+) produced by photolysis at 308 nm.