ON THE PHOTOCHEMISTRY OF X-RAY PRODUCED RADICALS TRAPPED IN FROZEN ETHANOL MATRICES |
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Authors: | Johan Moan |
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Institution: | Norsk Hydro's Institute for Cancer Research, Montebello, Oslo 3, Norway |
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Abstract: | Abstract— Ethanol and ethanol-water matrices were exposed to X-rays at 77K and the photochemistry and paths of radical conversion were investigated by EPR methods. The main X-ray induced radical, CH3ĊHOH, is probably photoionized by 254 nm light. The following radicals are produced during prolonged UV-irradiation of CH3ĊHOH radicals: ĊH3, ĊHO, H and 2 types of radicals giving singlet EPR spectra. One of these radicals (d) is bleachable with 580 nm light, ĊH3 and ĊH3ĊHOH being formed during the bleaching, the other one (e) is unbleachable and the most stable radical in the matrix during annealing. The CH3 radicals decay at 77 K (τ∽ 10 min) and produce CH3-CHOH radicals and the unbleachable radical (e). Stable H-atom signals were seen in X-irradiated ethanol-water mixtures (volume ratio 2:1) at 77 K. The H-atom signals increased during photobleaching of the trapped electrons in the matrix and during UV-photolysis of CH3CHOH radicals. |
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