Studies of BrCl by laser-induced fluorescence. Part 4.—Lower levels (v′⩽ 3) of the B3Π(0+) manifold

Abstract

Laser-excitation spectra of BrCl(B–X) with v′⩽ 3 have been assigned at high resolution. The magnitude of the collision-free lifetime for the v′= 1 state of BrCl(B) was τ₀= 41.5 ± 0.5 µs, in good agreement with the previous value, τ₀= 40.2 ± 1.8 µs for 3 ⩽v′⩽ 6. It has been demonstrated further that electronic self-quenching of the B state of BrCl was slow, with a rate constant in the range (2.2–3.9)× 10^–13 cm³ molecule^–1 s^–1. During the course of this study, the quenching rate constants with different bath gases have also been measured; the values ranged from (5.8 ± 0.2)× 10^–12 cm³ molecule^–1 s^–1 for O₂ down to (1.3 ± 0.2)× 10^–12 cm³ molecule^–1 s^–1 for Ar. Vibrational energy transfer plays a more important role than quenching in collisional processes, showing a strong dependence of rate constant upon v′, from (3.0 ± 0.2)× 10^–12 cm³ molecule^–1 s^–1 for the v′= 1 state, up to (2.1 ± 4.1)× 10^–10 cm³ molecule^–1 s^–1 for the v′= 6 state, according to previous work.