title: Rapid autoxidation forms highly oxidized RO2 radicals in the atmosphere.
abstract: Gas-phase oxidation routes of biogenic emissions, mainly isoprene and monoterpenes, in the atmosphere are still the subject of intensive research with special attention being paid to the formation of aerosol constituents. This laboratory study shows that the most abundant monoterpenes (limonene and α-pinene) form highly oxidized RO2 radicals with up to 12 O atoms, along with related closed-shell products, within a few seconds after the initial attack of ozone or OH radicals. The overall process, an intramolecular ROO→QOOH reaction and subsequent O2 addition generating a next R'OO radical, is similar to the well-known autoxidation processes in the liquid phase (QOOH stands for a hydroperoxyalkyl radical). Field measurements show the relevance of this process to atmospheric chemistry. Thus, the well-known reaction principle of autoxidation is also applicable to the atmospheric gas-phase oxidation of hydrocarbons leading to extremely low-volatility products which contribute to organic aerosol mass and hence influence the aerosol-cloud-climate system.
authors.affiliation: Leibniz-Institut für Troposphärenforschung, TROPOS, 04318 Leipzig (Germany); Department of Physics, P.O. Box 64, 00014 University of Helsinki (Finland).
authors.forename: Tuija
authors.initials: T
authors.lastname: Jokinen
authors.forename: Mikko
authors.initials: M
authors.lastname: Sipilä
authors.forename: Stefanie
authors.initials: S
authors.lastname: Richters
authors.forename: Veli-Matti
authors.initials: VM
authors.lastname: Kerminen
authors.forename: Pauli
authors.initials: P
authors.lastname: Paasonen
authors.forename: Frank
authors.initials: F
authors.lastname: Stratmann
authors.forename: Douglas
authors.initials: D
authors.lastname: Worsnop
authors.forename: Markku
authors.initials: M
authors.lastname: Kulmala
authors.forename: Mikael
authors.initials: M
authors.lastname: Ehn
authors.forename: Hartmut
authors.initials: H
authors.lastname: Herrmann
authors.forename: Torsten
authors.initials: T
authors.lastname: Berndt
keywords: atmospheric chemistry; autoxidation; mass spectrometry; radical reactions