A discharge-flow study of the self-reaction of IO

Abstract

A discharge-flow tube equipped with resonance-fluorescence detection for I atoms and chemiluminescence detection for O atoms has been used to investigate the kinetics of the reaction IO + IO → products (1) at T = 296 ± 1 K and P = 1.9–2.2 Torr. The rate constant was found to be k1 = (9.3 ± 1.9) × 10−11 cm3 molecule−1 s−1, where −d[IO]/dt = 2k1[IO]2 and the errors are 95% confidence limits of the mean of the experimental rate constants combined with an estimated further 20% error in other parameters. The determination of the rate constant for reaction (1) also required the investigation of the kinetics of the reaction IO + CF3 → products (2). The rate constant was found to be k2 = (1.6 ± 0.7) × 10−11 cm3 molecule−1 s−1, where errors are 95% confidence limits of the slope of the regression line of a second-order plot, combined with systematic errors of 20% for the calibration of [CF3]. I atoms are generated in reactions (1) and (2)IO + IO → 2I + O2→OIO + ICF3 + IO → CF3O + I