Collisional dynamics of the BrCl B 3Π(O+) state. I. Electronic quenching

Abstract

Electronic quenching of BrCl B 3Π(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, N2, O2, and Cl2. Quenching from a vibrationally thermalized, 300 K BrCl(B,v′) distribution by the noble gases N2, and Cl2 was slow with all rate coefficients less than 4.3±0.7×10−13 cm3 molecule−1 s−1 . The quenching by O2 was much faster with a rate coefficient of 6.5±0.6×10−12 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±0.1×10−13 cm3 molecule−1 s−1 for v′=0 to 1.4±0.3×10−10 cm3 molecule−1 s −1 for v′=6 under collisions with Cl2 and with rate coefficients ranging from 1.5±0.3×10−13 cm3 molecule−1 s−1 for v′=0 to 1.0± 0.4×10−10 cm3 molecule−1 s−1 for v′=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 v′≤6.