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| Titel |
On-line determination of ammonia at low pptv mixing ratios in the CLOUD chamber |
| VerfasserIn |
F. Bianchi, J. Dommen, S. Mathot, U. Baltensperger |
| 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 ; 5, no. 7 ; Nr. 5, no. 7 (2012-07-19), S.1719-1725 |
| Datensatznummer |
250003010
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| Publikation (Nr.) |
 copernicus.org/amt-5-1719-2012.pdf |
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| Zusammenfassung |
| A new instrument for the on-line determination of ammonia was developed.
Since ammonia is a rather sticky compound, sampling losses were minimised
with a new sampling device where the ammonia was transferred to the liquid
phase only 5 mm after the inlet tip. The liquid phase was then analyzed by
long pathlength absorption spectrophotometry using the Berthelot reaction with
phenol and hypochlorite as reagents. The measurements were made during the
CLOUD3 campaign at CERN where the influence of ammonia on the nucleation
rate was studied. At stable conditions the detection limit reached with this
instrument was 35 pptv (air flow rate of 2 l min−1, liquid flow rate of
0.3 ml min−1), although occasionally the instrument was affected by background
problems. The range of mixing ratios during this campaign was varied from
the background contamination (<35 pptv) up to around 2 ppbv. The measured
ammonia concentration was correlated with the rate of ammonia injected into
the chamber, but with a response time of several hours due to the high
tendency of ammonia to adsorb to or to desorb from surfaces. Since it was
found that ammonia strongly increases the nucleation rate already at the
lowest measured concentration, future work will focus on further decreasing
the detection limit of the instrument. |
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