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| Titel |
Intercomparison of peroxy radical measurements obtained at atmospheric conditions by laser-induced fluorescence and electron spin resonance spectroscopy |
| VerfasserIn |
H. Fuchs, T. Brauers, R. Häseler, F. Holland, D. Mihelcic, P. Müsgen, F. Rohrer, R. Wegener, A. Hofzumahaus |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 2, no. 1 ; Nr. 2, no. 1 (2009-03-09), S.55-64 |
| Datensatznummer |
250000427
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| Publikation (Nr.) |
 copernicus.org/amt-2-55-2009.pdf |
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| Zusammenfassung |
| Measurements of hydroperoxy radical (HO2) and organic peroxy radical (RO2)
concentrations were performed by two different techniques in the
atmospheric simulation chamber SAPHIR in Jülich, Germany. The first technique was the
well-established Matrix Isolation Electron Spin Resonance (MIESR), which provides absolute
measurements with a time resolution of 30 min and high accuracy (10%, 2 σ).
The other technique, ROxLIF, has been newly developed. It is based on the selective
chemical conversion of ROx radicals (HO2 and RO2) to OH, which
is detected with high sensitivity by laser-induced fluorescence (LIF). ROxLIF is
calibrated by quantitative photolysis of water vapor at 185 nm and
provides ambient measurements at a temporal resolution of 1 min and
accuracy of 20% (2 σ). The measurements of HO2 and RO2
obtained by the two techniques were compared for two types of atmospheric simulation
experiments. In one experiment, HO2 and CH3O2 radicals were produced
by photooxidation of methane in air at tropospheric conditions.
In the second experiment, HO2 and C2H5O2 were produced by ozonolysis
of 1-butene in air at dark conditions. The radical concentrations were within the range
of 16 to 100 pptv for HO2 and 12 to 45 pptv for RO2. Good
agreement was found in the comparison of the ROxLIF and MIESR measurements within
their combined experimental uncertainties. Linear regressions to the combined
data set yield slopes of 1.02±0.13 (1 σ) for RO2 and 0.98±0.08 (1 σ)
for HO2 without significant offsets. The results confirm the calibration
of the ROxLIF instrument and demonstrate that it can be applied with good accuracy for
measurements of atmospheric peroxy radical concentrations. |
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