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UBC Theses and Dissertations

Flash photolysis of the oxides of chlorine Dogra, Sneh Kumar


The production of vibrationally excited oxygen, O*₂, following the isothermal flash photolysis of C10₂, C1₂O and of the C10 free radical has shown to be due to the reactions of oxygen atom with C10₂ and C10 (1, 2). In both reactions, the energy, distribution in the products is markedly non-equilibrated with a large fraction of the energy liberated in the form of vibrational excitation of the oxygen molecule. The highest level of O*₂ produced corresponds to the exothermicity of the reactions. The rate constants for the production of O*₂ in levels v'’ = 6 ➛ v’’ = 13 are approximately equal. The relaxation of 0*₂ by C10₂, C10 and by C1 and 0 atoms has been studied and the exceptional efficiency of the atoms demonstrated. The rate constant for the bimolecular reaction of C10 radicals (10) was measured using C10₂, C1₂/0₂, C1₂0, C1₂0/C1₂ as sources of the radicals. The constancy of the value of 2.7 ± 0.3 x 10⁷ 1 mole⁻¹ sec⁻¹ obtained from all systems contrasts with the literature values of 6.2 x 10⁷ 1 mole⁻¹ sec⁻¹, 4.8 x 10⁷ 1 mole⁻¹ sec⁻¹ and 2.4 x 10⁷ 1 mole⁻¹ sec⁻¹, obtained from the first three systems. The chlorine and bromine photosensitised decomposition of C10₂ and C1₂0 have been studied and the extinction coefficient of C10 and BrO free radicals measured. Mechanisms have been proposed for all systems and all relevant rate constants have been measured. The results are listed below. [formulas omitted]

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