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At the crossroad of photochemistry and radiation chemistry: formation of hydroxyl radicals in diluted aqueous solutions exposed to ultraviolet radiation
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SYSNO ASEP 0508701 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title At the crossroad of photochemistry and radiation chemistry: formation of hydroxyl radicals in diluted aqueous solutions exposed to ultraviolet radiation Author(s) Tomanová, K. (CZ)
Přeček, M. (CZ)
Můčka, V. (CZ)
Vyšín, L. (CZ)
Juha, Libor (UFP-V) ORCID
Čuba, V. (CZ)Number of authors 6 Source Title Physical Chemistry Chemical Physics. - : Royal Society of Chemistry - ISSN 1463-9076
Roč. 19, č. 43 (2017), s. 29402-29408Number of pages 7 s. Language eng - English Country GB - United Kingdom Keywords coumarin-3-carboxylic acid ; photolysis ; phospholipids ; fluorescence ; mechanism ; lipids ; yield ; uv Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry Method of publishing Limited access Institutional support UFP-V - RVO:61389021 UT WOS 000414773100042 EID SCOPUS 85033555655 DOI 10.1039/c7cp05125e Annotation Formation yields of center dot OH radicals were precisely determined in aqueous solutions of coumarin-3-carboxylic acid and ferrous sulfate (i.e., Fricke dosimeter) exposed to 253.7 nm radiation delivered from a continuous source. Quantum yield of center dot OH radicals was determined as similar to 0.08, i.e., roughly one out of twelve photons, efficiently absorbed in UV-illuminated solutions, produced one center dot OH radical. Energetically, a water molecule should undergo a correlated action of at least two 4.9 eV photons delivering enough energy for direct H-OH dissociation (5.0-5.4 eV). We suggest a mechanism based on an interaction of two water molecules, both in long-living triplet states. An intermolecular transfer of excitation energy provided a sufficient amount of energy for the dissociation of one water molecule into center dot OH and H center dot radicals. In an aqueous solution of phospholipids, quantum yields of hydroperoxides formed under these irradiation conditions decreased with total effectively absorbed energy (i.e. a dose), similar to the radiation chemical yields obtained during an exposure to ionizing radiation, such as gamma rays from radionuclide sources. Under 253.7 nm irradiation, one center dot OH radical causes a peroxidation of 34 phospholipid molecules. This implicates chain mechanism of the reaction. Workplace Institute of Plasma Physics Contact Vladimíra Kebza, kebza@ipp.cas.cz, Tel.: 266 052 975 Year of Publishing 2020 Electronic address https://pubs.rsc.org/en/content/articlelanding/2017/CP/C7CP05125E#!divAbstract
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