Kinetics of reactions of C2H radical with acetylene, O2, methylacetylene, and allene in a pulsed Laval nozzle apparatus at T=103 K

The rate constants of the reactions of C2H radical with HCCH (k1), O2 (k2), CH3CCH (k3), and H2CCCH2 (k4) are measured at 103 K using a pulsed Laval nozzle supersonic expansion and the CH(A2Δ) chemiluminescence monitor method: k1=(1.3±0.3)×10−10, k2=(3.8±0.9)×10−11, k3=(2.7±0.6)×10−10, and k4=(2.5±0.6)×10−10 cm3 molecule−1 s−1. These values are compared to previous results and measurements in a continuous Laval nozzle apparatus (accompanying paper by Carty et al.). The non-Arrhenius behavior and possible implications of the results for atmospheric chemistry of Titan are discussed.