Kinetics of the Reactions of Cl(2P1/2) and Cl(2P3/2) Atoms with C2H6, C2D6, CH3F, C2H5F, and CH3CF3 at 298 K

Abstract

The title reactions were studied using laser flash photolysis in conjunction with laser-induced fluorescence techniques. Separate monitoring of the two spin−orbit states, Cl(2P1/2) and Cl(2P3/2), was used to measure the kinetics of the reactions of Cl(2P3/2) with C2H6, C2D6, CH3F, C2H5F, and CH3CF3, the reaction of Cl(2P1/2) with C2H6, and the relaxation of Cl(2P1/2) by collisions with C2H6, C2D6, CH3F, C2H5F, and CH3CF3. Measured reaction rate constants were (units of cm3 molecule-1 s-1): k(Cl(2P3/2) + C2H6) = (5.85 ± 0.55) × 10-11, k(Cl(2P3/2) + C2D6) = (1.87 ± 0.12) × 10-11, k(Cl(2P3/2)+ CH3F) = (2.7 ± 0.2) × 10-13, k(Cl(2P3/2) + CH3CH2F) = (6.8 ± 0.5) × 10-12, and k(Cl(2P3/2) + CH3CF3) < 1 × 10-14 cm3 molecule-1 s-1. Measured relaxation rate constants for deactivation of Cl(2P1/2) to Cl(2P3/2) via collisions with C2H6, C2D6, CH3F, C2H5F, CH3CF3, and CF4 were (1.22 ± 0.09) × 10-10, (2.4 ± 0.2) × 10-10, (6.4 ± 0.5) × 10-11, (1.9 ± 0.2) × 10-10, (2.0 ± 0.2) × 10-10, and (2.3 ± 0.4) × 10-11, respectively. Collisions of Cl(2P1/2) with C2H6 and C2D6 resulted mainly in the relaxation of Cl(2P1/2) to Cl(2P3/2) and not in the reactive formation of HCl (DCl). The rate constant of the reactive path for Cl(2P1/2) + C2H6 was < 3 × 10-11 cm3 molecule-1 s-1.