Studies of labile molecules with a tunable dye laser: Laser excitation spectrum of BrF (B3Π(0+)-X1Σ+)

The B³Π(0⁺) ← X¹Σ⁺ absorption spectrum of BrF (4850–5200 Å) has been observed by the technique of laser emission spectroscopy. Fluorescence was excited by a pulsed, scannable dye laser with a 0.1 Å bandwidth. Rotational analysis has been carried out for six bands of the v″ = 0 progression (8 ≥ v′ ≥ 3) of ⁷⁹BrF and ⁸¹BrF. Rotational constants for the B³Π(0⁺) state are reported for the first time. RKR potential energy curves for both states, and an array of Franck-Condon factors and r-centroids for the transition, have been calculated. Bands with v′ > 8 were not observed in fluorescence owing to the onset of predissociation near J′ = 28 of the v′ = 8 level. An upper limit for the ground state dissociation energy is D₀″ (BrF, X¹Σ⁺) ≤ 20 880 cm^?1.