Kinetics of the CH3O2 + HO2 reaction: A temperature and pressure dependence study using chemical ionization mass spectrometry

A temperature and pressure kinetic study for the CH3O 2 + HO2 reaction has been performed using the turbulent flow technique with a chemical ionization mass spectrometry detection system. An Arrhenius expression was obtained for the overall rate coefficient of CH 3O2 + HO2 reaction: k(T) = (3.82 -1.61+2.79) × 10-13 exp|(-781 ± 127)/T ] cm-3 molecule-1 s-1. A direct quantification of the branching ratios for the O3 and OH product channels, at pressures between 75 and 200 Torr and temperatures between 298 and 205 K, was also investigated. The atmospheric implications of considering the upper limit rate coefficients for the O3 and OH branching channels are observed with a significant reduction of the concentration of CH 3OOH, which leads to a lower amount of methyl peroxy radical. © 2007 Wiley Periodicals, Inc.