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| Titel |
A high-resolution mass spectrometer to measure atmospheric ion composition |
| VerfasserIn |
H. Junninen, M. Ehn, T. Petäjä, L. Luosujärvi, T. Kotiaho, R. Kostiainen, U. Rohner, M. Gonin, K. Fuhrer, M. Kulmala  , D. R. Worsnop |
| 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 ; 3, no. 4 ; Nr. 3, no. 4 (2010-08-17), S.1039-1053 |
| Datensatznummer |
250001218
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| Publikation (Nr.) |
 copernicus.org/amt-3-1039-2010.pdf |
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| Zusammenfassung |
| In this paper we present recent achievements on developing and testing a tool
to detect the composition of ambient ions in the mass/charge range up to
2000 Th. The instrument is an Atmospheric Pressure Interface Time-of-Flight
Mass Spectrometer (APi-TOF, Tofwerk AG). Its mass accuracy is better than
0.002%, and the mass resolving power is 3000 Th/Th. In the data analysis,
a new efficient Matlab based set of programs (tofTools) were developed,
tested and used. The APi-TOF was tested both in laboratory conditions and
applied to outdoor air sampling in Helsinki at the SMEAR III station.
Transmission efficiency calibrations showed a throughput of 0.1–0.5% in
the range 100–1300 Th for positive ions, and linearity over 3 orders of
magnitude in concentration was determined. In the laboratory tests the
APi-TOF detected sulphuric acid-ammonia clusters in high concentration from
a nebulised sample illustrating the potential of the instrument in revealing
the role of sulphuric acid clusters in atmospheric new particle formation.
The APi-TOF features a high enough accuracy, resolution and sensitivity for
the determination of the composition of atmospheric small ions although the
total concentration of those ions is typically only 400–2000 cm−3.
The atmospheric ions were identified based on their exact masses, utilizing
Kendrick analysis and correlograms as well as narrowing down the potential
candidates based on their proton affinities as well isotopic patterns. In
Helsinki during day-time the main negative ambient small ions were inorganic
acids and their clusters. The positive ions were more complex, the main
compounds were (poly)alkyl pyridines and – amines. The APi-TOF provides
a near universal interface for atmospheric pressure sampling, and this key
feature will be utilized in future laboratory and field studies. |
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