Laser induced fluorescence studies of the reactions of O(1D2) with N2, O2, N2O, CH4, H2, CO2, Ar, Kr and n-C4H10

A laser flash photolysis–laser-induced fluorescence (LIF) technique has been used to study the kinetics of the reactions of electronically excited oxygen atoms, O(1D2), with N2, O2, N2O, CH4, H2, CO2, Ar, Kr and n-C4H10 over the temperature range 195–673 K. The majority of studies employed direct detection of O(1D2) atoms using vacuum ultraviolet LIF at 115.2 nm, whereas some studies employed LIF detection of OH generated from reaction of O(1D2) with a H atom donor species as a marker for O(1D2). The bimolecular rate coefficient for reaction with N2 (kN2) is well described by the Arrhenius expression kN2 = (2.2 ± 0.3) × 10−11exp{(118 ± 21)/T} (95% confidence level), in good agreement with two other new studies reported in this issue, but giving significantly higher values of kN2 than previously measured, with important implications for production rates of OH and NO radicals in the atmosphere. At 295 K the following rate coefficients were obtained (in units of cm3 molecule−1 s−1, 95% confidence level including estimated systematic errors): kN2 = (3.06 ± 0.25) × 10−11, kO2 = (3.8 ± 0.4) × 10−11, kN2O = (1.07 ± 0.1) × 10−10, kCH4 = (1.4 ± 0.2) × 10−10, kH2 = (1.5 ± 0.1) × 10−10, kCO2 = (1.4 ± 0.1) × 10−10, kAr = (8 ± 3) × 10−13, kKr = (9 ± 1) × 10−12 and kn-C4H10 = (4.55 ± 0.2) × 10−10, in good agreement with the new studies reported in this issue, and with previous measurements, where available. An analysis of the correlation between the cross-section for O(1D2) removal and the ionisation potential of the collision partner suggests at least two mechanisms operate for the removal of O(1D2).