Abstract
A new method is proposed to determine the calibration factor (CF) of methyl and ethyl peroxy radicals in a chemical amplifier. The radical source comes from the reactions of excess methane and ethane, respectively, with known concentrations of OH radicals generated by the photolysis of water vapor at 184.9 nm in air in a flow tube. This yields a mixed radical source with equal amounts of HO2 and RO2 (R = CH3, C2H5). The CF for RO2 can be derived from the CF for HO2 and an average CF for the mixed radicals. The reliability of the method was evaluated by comparing the CF ratios of RO2 to HO2 obtained from both the experiments and theoretical calculations.
