A highly sensitive method for time-resolved detection of O(1D) applied to precise determination of absolute O(1D) reaction rate constants and O(3P) yields

Abstract

We demonstrate detection, in the gas-phase, of O(¹D₂) at concentrations down to 10⁷ cm⁻³ and develop this new method for time-resolved kinetic studies allowing both the total removal rate of O(¹D₂), of up to 1.5 × 10⁶ s⁻¹, and the fraction quenched to O(³P_J) by species X, k_q/k(X), to be determined precisely from a single time profile: at 295 K we find, k(O(¹D₂) + N₂O) = (1.43 ± 0.08) × 10⁻¹⁰ cm³ s⁻¹ with k_q/k(N₂O) = 0.056 ± 0.009; k(O(¹D₂) + C₂H₂) = (3.1 ± 0.2) × 10⁻¹⁰ cm³ s⁻¹ with k_q/k(C₂H₂) = 0.020 ± 0.010; k_q/k(H₂O) < 0.003 for O(¹D₂) + H₂O.