Temperature dependence of the reaction of ClO and HO2 radicals

The rate constant for the reaction of ClO with HO2, k1, was measured over the temperature range 235⩽T⩽393 K using laser magnetic resonance detection to monitor directly the concentrations of both reactants. Measurements were made at low pressures, 0.8⩽P⩽3.4 Torr, in three different discharge-flow tubes, 14.0, 25.4, and 36.7 mm i.d., and with two different sources for ClO radicals, Cl+O3 and Cl+Cl2O. The observed temperature dependence is fitted by the expression, k1=3.3×10−11 exp(−850/T)+4.5×10−12 (T/300)−3.7 cm3 molecule−1 s−1 The products of the reaction were not detected but the possible channels HOCl+O2 and HCl+O3 have important implications for stratospheric chemistry.