Rate constants for the reaction of OH radicals with ethylene over the temperature range 299–425 °K

Absolute rate constants for the reaction of OH radicals with ethylene have been determined, using a flash photolysis–resonance fluorescence technique, over the temperature range 299–425 °K at total pressures of 25–663 torr of argon. The rate constants k2 were observed to be pressure dependent below ∼225 torr total pressure, in agreement with other recent studies. The rate constants were independent of total pressure over the range 225–663 torr of argon, and the Arrhenius expression obtained from data over this pressure range was k2=2.18×10−12 e(770±300)/RT cm3 molecule−1⋅sec−1 with a value at 299 °K of k2= (7.85±0.79) ×10−12 cm3 molecule−1⋅sec−1. This room temperature high pressure rate constant is in good agreement with a recent relative rate determination carried out at atmospheric pressure.