Kinetics and mechanism of the OH + CIO2reaction

✍ Scribed by G. Poulet; H. Zagogianni; G. Le Bras

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 629 KB
• Volume: 18
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550180805

✦ Synopsis

The rate constant k , for the reaction of OH radicals with C102 molecules was measured in a discharge flow system over the temperature range 293 5 T < 473 K and at low pressures, 0.5 5 P 5 1.4 torr, using electron paramagnetic resonance or laser-induced fluorescence to monitor the pseudo first-order decay of OH concentrations. At 293 K, the value obtained for kl was (7.2 _t 0.5) x 10.'' cm3 molecule-' s-'. Within the temperature range of this study, a negative temperature dependence was observed: k , = (4.50 t 0.75) x exp[(804 t 114)/T] cm3 molecule-'s-'. HOCl was detected by mass spectrometry as a product of the reaction and was titrated using OH + Clz as a source in the calibration experiments. A simulation of the mechanism of the OH + CIOz reaction indicated that HOCl was mainly produced in the first reaction step. Both this result and the observed T dependence of k , suggest that this reaction proceeds via an intermediate adduct with a cyclic geometry.