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| Titel |
Measurement of peroxy radicals by chemical ionization mass spectrometry with a corona ion source |
| VerfasserIn |
Weihao Wang, Yee Jun Tham, Zhe Wang, David Tanner, Chuan Yu, Tao Wang |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143722
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| Publikation (Nr.) |
 EGU/EGU2017-7472.pdf |
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| Zusammenfassung |
| Peroxy radicals including hydroperoxyl (HO2) and organic peroxy (RO2) radicals play key
roles in atmospheric radical chemistry. However, accurate measurement of these radicals
remains a challenge due to low concentration, strong activity and not well known
intereference. Here we present the measurement of ambient peroxy (HO2+RO2) radicals at
an urban site in Hong Kong using chemical ionization mass spectrometry (CIMS) with a
corona ion source. The peroxy radicals are titrated by NO into OH and further converted
into H2SO4, which is detected by the CIMS through the reaction with NO3− ions.
Although the corona ion source has advantages as a non-radiative source and with a low
cost, it has a higher background and is less stable compared to the widely used
radioactive source. We have improved the design of the corona ion source. The detection
limit for the corona ion source is 1×108 molecules/cm3 for an integration time
of 1 min. Hexafluoropropylene (C3F6), which is widely used as OH scavenger,
has been shown to produce HO2 through its reaction with OH in presence of high
concentrations of NO, leading to high instrument background for HO2. The measurement
results of ambient HO2 and RO2 during a photochemical episode will be presented. |
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