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| Titel |
The charging of neutral dimethylamine and dimethylamine–sulfuric acid clusters using protonated acetone |
| VerfasserIn |
K. Ruusuvuori, P. Hietala, O. Kupiainen-Määttä, T. Jokinen, H. Junninen, M. Sipilä, T. Kurtén, H. Vehkamäki |
| 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 ; 8, no. 6 ; Nr. 8, no. 6 (2015-06-25), S.2577-2588 |
| Datensatznummer |
250116441
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| Publikation (Nr.) |
 copernicus.org/amt-8-2577-2015.pdf |
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| Zusammenfassung |
| Sulfuric acid is generally considered one of the most important substances
taking part in atmospheric particle formation. However, in typical
atmospheric conditions in the lower troposphere, sulfuric acid and water
alone are unable to form particles. It has been suggested that strong bases
may stabilize sulfuric acid clusters so that particle formation may occur.
More to the point, amines – strong organic bases – have become the subject
of interest as possible cause for such stabilization. To probe whether
amines play a role in atmospheric nucleation, we need to be able to measure
accurately the gas-phase amine vapour concentration. Such measurements often
include charging the neutral molecules and molecular clusters in the sample.
Since amines are bases, the charging process should introduce a positive
charge. This can be achieved by, for example, using chemical ionization with
a positively charged reagent with a suitable proton affinity. In our study,
we have used quantum chemical methods combined with a cluster dynamics code
to study the use of acetone as a reagent ion in chemical ionization and
compared the results with measurements performed with a chemical ionization
atmospheric pressure interface time-of-flight mass spectrometer
(CI-APi-TOF). The computational results indicate that protonated acetone is
an effective reagent in chemical ionization. However, in the experiments the
reagent ions were not depleted at the predicted dimethylamine
concentrations, indicating that either the modelling scheme or the
experimental results – or both – contain unidentified sources of error. |
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