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@ARTICLE{Albrecht:862048,
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 ionisation mass spectrometry},
journal = {Atmospheric measurement techniques},
volume = {12},
number = {2},
issn = {1867-8548},
address = {Katlenburg-Lindau},
publisher = {Copernicus},
reportid = {FZJ-2019-02414},
pages = {891 - 902},
year = {2019},
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 ionisation combined with a
high-resolution time-of-flight mass spectrometer (Aerodyne
Research Inc.) employing bromide as the primary ion is
presented. The sensitivity reached is equal to 0.005×108
HO2 cm−3 for 106 cps of bromide and 60 s of
integration time, which is below typical HO2 concentrations
found in the atmosphere. The detection sensitivity of the
instrument is affected by the presence of water vapour.
Therefore, a water-vapour-dependent calibration factor that
decreases approximately by a factor of 2 if the water vapour
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)×108 molecules cm−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
in comparison to the well-established laser-induced
fluorescence (LIF) technique for measurements of HO2. A
highly 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 experiments allowed
for testing the instrument's behaviour in the presence of
atmospheric concentrations of H2O, NOx, and O3. No
significant interferences from these species were observed.
All of these facts demonstrate a reliable measurement of HO2
by the chemical ionisation mass spectrometer presented.},
cin = {IEK-8},
ddc = {550},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000458115600002},
doi = {10.5194/amt-12-891-2019},
url = {https://juser.fz-juelich.de/record/862048},
}