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@ARTICLE{Fuchs:151451,
author = {Fuchs, H. and Acir, I.-H. and Bohn, B. and Brauers, T. and
Dorn, H.-P. and Häseler, R. and Hofzumahaus, A. and
Holland, F. and Kaminski, M. and Li, Xin and Lu, K. and
Lutz, A. and Nehr, Sascha and Rohrer, F. and Tillmann, R.
and Wegener, R. and Wahner, A.},
title = {{OH} regeneration from methacrolein oxidation investigated
in the atmosphere simulation chamber {SAPHIR}},
journal = {Atmospheric chemistry and physics / Discussions},
volume = {14},
number = {4},
issn = {1680-7375},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2014-01397},
pages = {5197 - 5231},
year = {2014},
abstract = {Hydroxyl radicals (OH) are the most important reagent for
the oxidation of trace gases in the atmosphere. OH
concentrations measured during recent field campaigns in
isoprene rich environments were unexpectedly large. A number
of studies showed that unimolecular reactions of organic
peroxy radicals (RO2) formed in the initial reaction step of
isoprene with OH play an important role for the OH budget in
the atmosphere at low mixing ratios of nitrogen monoxide
(NO) of less than 100 pptv. It has also been suggested that
similar reactions potentially play an important role for RO2
from other compounds. Here, we investigate the oxidation of
methacrolein (MACR), one major oxidation product of
isoprene, by OH in experiments in the simulation chamber
SAPHIR under controlled atmospheric conditions. The
experiments show that measured OH concentrations are
approximately $50\%$ larger than calculated by current
chemical models for conditions of the experiments (NO mixing
ratio of 90 pptv). The analysis of the OH budget reveals a
so far unaccounted OH source, which is correlated with the
production rate of RO2 radicals from MACR. In order to
balance the measured OH destruction rate, (0.77±0.3) OH
radicals need to be additionally reformed from each OH that
has reacted with MACR. The strong correlation of the missing
OH source with the production of RO2 radicals is consistent
with the concept of OH formation from unimolecular
isomerization and decomposition reactions of RO2. The
comparison of observations with model calculations gives a
lower limit of 0.03 s−1 for the reaction rate constant, if
the OH source is attributed to an isomerization reaction of
one RO2 species formed in the MACR+OH reaction as suggested
in literature. This fast isomerization reaction would be
competitive to the reaction of this RO2 species with minimum
150 pptv NO},
cin = {IEK-8},
ddc = {550},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {233 - Trace gas and aerosol processes in the troposphere
(POF2-233) / 243 - Tropospheric trace substances and their
transformation processes (POF3-243) / HITEC - Helmholtz
Interdisciplinary Doctoral Training in Energy and Climate
Research (HITEC) (HITEC-20170406)},
pid = {G:(DE-HGF)POF2-233 / G:(DE-HGF)POF3-243 /
G:(DE-Juel1)HITEC-20170406},
typ = {PUB:(DE-HGF)16},
doi = {10.5194/acpd-14-5197-2014},
url = {https://juser.fz-juelich.de/record/151451},
}