Kinetics of the Reactions of CH2(ã1A1) with CH3C2H, HCN, CO2, N2O and COS

The reactions of CH2(ã1A1) with CH3C2H, HCN, CO2, N2O and COS are investigated at room temperature. CH2(ã1A1) is generated by pulsed laser photolysis of CH2CO. Overall removal rate constants are derived from concentration profiles under first order reaction conditions using direct, time resolved LIF detection of CH2(ã1A1). The second order rate constants are found in units of 1013 cm2/mol s to be 24, 18, 2.0, 3.8 and 20, respectively. — The contributions of physical quenching to the removal of CH2(ã1A1) are determined by monitoring directly the formation of CH2(X̃3B1) with the LMR absorption technique. The branching ratios of collision induced intersystem crossing versus total consumption of 1CH2 are 0.24, 0.32, 0.67, 0.46 and 0.29 for the five reactants.