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Physicochemical parameters: a laser photolysis - resonance fluorescence study

Laser flash photolysis coupled to resonance-fluorescence detection of I atoms was used to measure the rate coefficients for the reactions: I + O3; IO + O2 (R1), O + I2; IO + I (R6) and I + NO2 + M; INO2 + M (R7). All experiments were conducted under pseudo first-order conditions, and the accuracy of the results was enhanced by online determination of reagent concentrations by optical absorption. Bimolecular rate coefficients for reactions (R1) and (R6) were determined to be k1 = (1.28 ± 0.06) ?10-12 and k6 = (1.2 ± 0.1) ?10-10 cm3 molecule 1s-1 at 298 ± 2K, independent of pressure. Rate coefficients for the termolecular reaction (R7), also at 298 ± 2K, were found to be in the falloff region between 3rd and 2nd order behaviour and, when combined with other datasets obtained at higher and lower pressures, were adequately described by a simplified Troe function with the parameters: k7,0(He, 330K) = 1.48 ?10-31 cm6 molecule-2s-1, FC(He) = 0.43, and k7; = 1.1 ?10-10 cm3 molecule-1s-1 for He as bath gas. In N2 (or air) the following parameters were obtained k7,0(N2, 300 K) = 3.2 ?10-31cm6 molecule-2s-1, FC(N2) = 0.48, with k7; set to 1.1 ?10-10cm3 molecule 1s-1 as obtained from analysis of the falloff curve obtained in He

Citation: M.E. Tucceri, T.J. Dillon, and J.N. Crowley, J.N., A Laser Photolysis - Resonance Fluorescence Study of the Reactions: I + O3 -> IO + O2, O + I2 -> IO + I, and I + NO2 + M -> INO2 + M at 298K, Phys. Chem. Chem. Phys., 7, 1657 - 1663, 2005

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Max-Planck-Institut fur Chemie, Division of Atmospheric Chemistry
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55020 MAINZ