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@ARTICLE{Albrecht:857601,
author = {Albrecht, Sascha R. and Novelli, Anna and Hofzumahaus,
Andreas and Kang, Sungah and Baker, Yare and Mentel, Thomas
and Wahner, Andreas and Fuchs, Hendrik},
title = {{M}easurements of hydroperoxy radicals
$({HO}\<sub\>2\</sub\>)$ at atmospheric concentrations using
bromide chemical ionization mass spectrometry},
journal = {Atmospheric measurement techniques discussions},
volume = {amt-2018-195},
issn = {1867-8610},
address = {Katlenburg-Lindau},
publisher = {Copernicus},
reportid = {FZJ-2018-06586},
pages = {1 - 19},
year = {2018},
abstract = {Hydroxyl and hydroperoxy radicals are key species for the
understanding of atmospheric oxidation processes. Their
measurement is challenging due to their high reactivity,
therefore very sensitive detection methods are needed.
Within this study, the measurement of hydroperoxy radicals
(HO2) using chemical ionization combined with an high
resolution time of flight mass spectrometer (Aerodyne
Research Inc.) employing bromide as primary ion is
presented. The 1σ limit of detection of
4.5×107moleculescm−3 for a 60s measurement is below
typical HO2 concentrations found in the atmosphere. The
detection sensitivity of the instrument is affected by the
presence of water vapor. Therefore, a water vapor dependent
calibration factor that decreases approximately by a factor
of 2 if the water vapor mixing ratio increases from 0.1 to
$1.0\%$ needs to be applied. An instrumental background most
likely generated by the ion source that is equivalent to a
HO2 concentration of 1.5±0.2×108moleculescm−3 is
subtracted to derive atmospheric HO2 concentrations. This
background can be determined by overflowing the inlet with
zero air. Several experiments were performed in the
atmospheric simulation chamber SAPHIR at the
Forschungszentrum Jülich to test the instrument performance
by comparison to the well-established laser-induced
fluorescence (LIF) technique for measurements of HO2. A high
linear correlation coefficient of R2=0.87 is achieved. The
slope of the linear regression of 1.07 demonstrates the good
absolute agreement of both measurements. Chemical conditions
during 15 experiments allowed testing the instrument’s
behavior in the presence of atmospheric concentrations of
H2O, NOx and O3. No significant interferences from these
species were observed. All these facts are demonstrating a
reliable measurement of HO2 by the chemical ionization mass
spectrometer presented.},
cin = {IEK-8},
ddc = {550},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {243 - Tropospheric trace substances and their
transformation processes (POF3-243)},
pid = {G:(DE-HGF)POF3-243},
typ = {PUB:(DE-HGF)16},
doi = {10.5194/amt-2018-195},
url = {https://juser.fz-juelich.de/record/857601},
}