The near-infrared, visible and ultraviolet photochemistry of ozone substrate complexes studied using matrix isolation Fourier transform infrared spectroscopy

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Ohio State University

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The formation of complexes between ozone and a number of substrates and the subsequent photochemically induced reactions have been studied by FTIR in low temperature (ca. 14 K) argon matrices. Formation of the complex changes the photochemistry of ozone and leads, with long wavelength irradiation, to the transfer of oxygen atoms. Photolysis with light of varying wavelengths allows a photochemical pathway to be discerned so that, for example, photolysis of the ozoneiodoethane complex with near-infrared radiation forms iodosoethane, $C_{2}H_{5}IO$. Subsequent photolysis $(\lambda > 650 nm)$ causes iodosoethane to react with excited oxygen and form iodylethane, $C_{2}H_{5}IO_{2}$. Iodosoethane is converted to ethyl hypoiodide, $C_{2}H_{5}OI$, by radiation in the region $350 < \lambda < 550 nm$. Photolysis in this region also dissociates iodosoethane into hydrogen hypoiodide and ethene, which can react with oxygen atoms to form ethanal. Finally Pyrex-filtered radiation $(\lambda > 290 nm)$ can dissociate ethyl hypoiodide into ethanal and hydrogen iodide. This method also leads to information about the interaction between the carbonyl group of ethanal with hydrogen iodide and hydrogen hypoiodide. Similar studies have been carried out to observe differences in photochemistry and photoproducts as a result of the presence of fluorine in the substrates. Some of the substrates used include pentafluoroiodoethane, $C_{2}F_{5}I$, 2-trifluoroiodoethane, $CF_{3}CH_{2}I$, 1, 1, 2, 2-tetrafluoroiodoethane, $CF_{2}HCF_{2}I$ and chloroiodoethane, $CH_{2}CII$.


Author Institution: University College London, 20 Gordon Street, London, WCIH OAJ, U. K.