COLLISIONAL DYNAMICS OF THE BRCL B PI-3(O+) STATE .1. ELECTRONIC QUENCHING

Electronic quenching of BrCl B3II(O+) was studied in pulsed and steady-state laser induced fluorescence experiments. BrCl(B) deactivation rate coefficients were determined as a function of vibrational quantum number for the following collision partners: He, Ne, Ar, Kr, N 2, O2, and Cl2. Quenching from a vibrationally thermalized, 300 K BrCl (B,υ′) distribution by the noble gases N 2, and Cl2 was slow with all rate coefficients less than 4.3 ± 0.7 X 10-13 cm3 molecule-1 1 s -1. The quenching by O2 was much faster with a rate coefficient of 6.5 ± 0.6 X 10-12 cm3 molecule -1 s-1. The quenching of BrCl(B), under single collision conditions, depends strongly on vibrational quantum number of BrCl(B), with rate coefficients ranging from 4.3 ± 0.1X10-13 cm3 molecule-1 s-1 for υ′ = O to 1.4 ± 0.3 X 10-10 cm3 molecule-1 s -1 for υ′ = 6 under collisions with Cl2 and with rate coefficients ranging from 1.5 ± 0.3X10-13 cm3 molecule-1 s -1 for υ′ = 0 to 1.0 ± 0.4X10-10 cm3 molecule-1 s-1 for υ′ = 6 under collisions with He. Several mechanisms for the electronic deactivation of BrCl (B) are discussed. The radiative lifetime of BrCl(B) was determined to be 38.7 ± 1.7 μs, independent of vibrational level for υ′≤6. © 1990 American Institute of Physics.