Absolute Rate Constants for the Reactions of O(3P) Atoms with C2H4 and C2D4

Abstract

Rate constants for the reactions of O(3 P) with C2H4 and with C2D4 were determined at 298±2°K using pulsed vacuum‐uv photolysis. Both NO 2 * and CO 2 * chemiluminescence were used to monitor decays of O atoms. The decay rates of O atoms in the presence of a large excess of C2H4 or C2D4 were independent of the initial concentration of O atoms in the range of approximately 109–1012 O atoms cm−3 and were linearly dependent on the reactant concentration. From these measurements, rate constants were determined to be 6.25 (± 0.63)× 10 −13 cm 3 molecule −1 · sec −1 for O+C 2 H 4 , and 5.6 (± 0.56)× 10 −13 cm 3 molecule −1 · sec −1 for O+C 2 D 4 . The present value for O+C2H4 agrees well with that measured previously in this laboratory and confirms the validity of the pulsed vacuum‐uv photolysis‐chemiluminescence method.