The rate constant for the reaction HO2+O3→OH+2O2 was investigated in a discharge–flow system at room temperature. HO2 was produced from the reaction sequence Cl+CH3OH→CH2OH+HCl and CH2OH+O2→HO2+CH2O. HO2 was detected by the OH(A–X) fluorescence produced from photodissociative excitation of HO2 at 147 nm. A computer modeling of the reaction kinetics occurring in the flow tube was carried out to confirm that contributions from secondary reactions were negligible at low HO2 concentrations. The rate constant was determined from first order decay of HO2 in excess O3. The measured reaction rate constant of HO2+O3 is (1.9±0.3)×10−15 cm3 molecule−1 s−1, which agrees well with published data.

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