Kinetics of the OH radical formation in pulse radiolysis of Ar–H 2O gaseous mixtures

Abstract

The gaseous mixtures of Ar–H 2O were electron pulse (12 ns) irradiated and formation/decay kinetics of the hydroxyl radicals was studied using time-resolved emission spectroscopy. The quenching rate constants for both excited argon atoms (Ar *) and OH( 2 Σ +) radicals were found in good agreement with the literature values. The rate constants k 1a=8.1±0.4×10 −10 cm 3 s −1 and k 5=7.61±0.28×10 −10 cm 3 s −1 were determined for the first time. The very fast termolecular process Ar *+Ar+H 2O→products with k=1.8±1.4×10 −29 cm 6 s −1 was demonstrated to occur and must be included into the reaction mechanism.