THE D'-]A' TRANSITION IN BRF

The most intense band system in the emission spectrum of BrF in moderate pressures (<1 atm) of inert buffer gases occurs with peak intensity near 3540 Å. This transition is designated D′ → A′, in which the upper state is the lowest Ω = 2 state correlating with Br+ + F-, and the lower is the lowest excited valence state, the Ω = 2 component of a 3Π. An extensive rotational analysis, including ∼900 assigned lines in 79BrF and 81BrF, yields the following constants (cm-1) for the D′ state in 79BrF: ωe = 307.98(9), ωeχe = 1.53(5), Be = 0.15524(1), αe = 5.98(3) × 10-4, and Re = 2.6630(1) A ̊. Since the data sample only the intermediate v″ range 8-13, the equilibrium constants of the A′ state are not well determined. However, the properties of this state are in line with trends in other diatomic halogens, with BrF(A′) being the most deeply bound A′ state yet analyzed (De ≈ 5200 cm-1). © 1990.