Kinetic Study of OH + OH and OD + OD Reactions

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 1999-09, Vol.103 (35), p.7017-7025
• Main Authors: Bedjanian, Y, Le Bras, G, Poulet, G
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp991146r

The kinetics of the disproportionation reactions of OH and OD radicals, OH + OH → O + H2O (1), OD + OD → O + D2O (3), have been studied by the mass spectrometric discharge-flow method at temperatures between 233 and 360 K and at total pressure of 1 Torr of helium. The following Arrhenius expressions were obtained:  k 1 = (7.1 ± 1.0) × 10-13exp[(210 ± 40)/T] and k 3 = (2.5 ± 0.5) × 10-13exp[(170 ± 60)/T] cm3 molecule-1 s-1. Reaction 4 between OH and OD radicals was also investigated and the same rate constant as for reaction 1 was measured. Both the observed temperature dependence of k 1 and the measured kinetic isotopic effect (k 1/k 3) are compatible with the mechanism proposed in a previous theoretical study (Harding, L. B.; Wagner, A. F. 22nd International Symposium on Combustion, 1988). In addition, a temperature-independent rate coefficient of (1.20 ± 0.25) × 10-10 cm3 molecule-1 s-1 was measured for the reaction D + NO2 → OD + NO in the temperature range 230−365 K.