Rate coefficients for the reaction of C 2H with O 2 at 90 K and 120 K using a pulsed Laval nozzle apparatus

Abstract

Absolute rate coefficients for the reaction of C 2H with O 2 are measured at 90 K and 120 K by using a pulsed Laval nozzle apparatus with laser ionization, time-of-flight mass spectrometry (TOF-MS). The C 2H radicals are generated by laser photolysis of C 2H 2 at 193 nm, and the products of the reaction with O 2 and C 2H 2, HCCO and C 4H 2, respectively, are directly detected by laser ionization at 118 nm. Rate coefficients of (9.0±2.0)×10 −11 and (5.0±1.5)×10 −11 cm 3 molecule −1 s −1 are obtained at 90 K and 120 K for the C 2H+O 2 reaction, respectively, by detecting the rise of the product HCCO.