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Adduktbildung von OH-Radikalen und Folgereaktionen mit O2 und NOx zur atmosphärischen Regenerierung von OH

Schlußßbericht zum Forschungsvorhaben FKZ 07 EU 705A/0
Adduct formation of OH radicals and subsequent reactions with O2 and NOx leading to atmospheric regeneration of OH
: Zetzsch, C.; Koch, R.; Knispel, R.; Siese, M.; Bohn, B.
: Bundesministerium für Forschung und Technologie -BMFT-, Bonn

1995, 26 S.
Fraunhofer ITA ( ITEM) ()
air pollution; aromatic compound; atmospheric chemistry; hydrocarbon; kinetics; oxidation; photochemistry; physical chemistry; pollutant; theoretical chemistry

Unsaturated hydrocarbons, aromatics in particular, are strongly involved in the formation of ozone by tropospheric photochemistry. Additon of OH is known to initiate the corresponding chain reactions. Prior to EUROTRAC, the reaction of the OH-adduct with O2 was believed to be the main consecutive step, though its rate constant was still unknown, and only preliminary data was available for the alternative reactions with NO and NO2. Resonance fluorescence and cw-UV-laser absorption were employed to study time profiles of OH in the presence of various aromatics, acetylene and isoprene (the OH-adduct of benzene was studied directly by laser absorption). The O2- and NO2-reactivities of the OH-adducts of the aromatics were determined; NO turned out to be unreactive. Our results show that O2 is the reactant of the OH-adducts relevant for the troposphere, and this was further confirmed by smog chamber experiments on benzene, toluene and p-sylene. (abstract truncated)