Absolute rates of the collisional quenching of O(2 1D 2) by CF 2Cl 2 and CFCl 3

Abstract

The first absolute rate measurements for the collisional quenching of the electronically excited oxygen atom, O(2 1D 2), by the atmospherically important fluorocarbons, CF 2Cl 2 and CFCl 3, are reported. O(2 1D 2) was generated by the repetitive pulsed irradiation of O 3 in the Hartley-band continuum and monitored photoelectrically in absorption by time-resolved attenuation of atomic resonance radiation at λ = 115.2 nm (O(3 1D 2 0) → O(2 1D 2)). The resulting absolute second order rate constants are found to be (4.8 ± 0.6) × 10 −10 and (7.7 ± 0.9) × 10 −10 cm 3 molecule −1 s −1 at 300 K for CF 2Cl 2 and CFCl 3, respectively. The resulting absolute data are compared with some previous relative rate data obtained from steady photolysis measurements.