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| Titel |
Experimental investigation of ion–ion recombination under atmospheric conditions |
| VerfasserIn |
A. Franchin, S. Ehrhart, J. Leppä, T. Nieminen, S. Gagné, S. Schobesberger, D. Wimmer, J. Duplissy, F. Riccobono, E. M. Dunne, L. Rondo, A. Downard, F. Bianchi, A. Kupc, G. Tsagkogeorgas, K. Lehtipalo, H. E. Manninen, J. Almeida, A. Amorim, P. E. Wagner, A. Hansel, J. Kirkby, A. Kürten, N. M. Donahue, V. Makhmutov, S. Mathot, A. Metzger, T. Petäjä, R. Schnitzhofer, M. Sipilä, Y. Stozhkov, A. Tomé, V.-M. Kerminen, K. Carslaw, J. Curtius, U. Baltensperger, M. Kulmala  |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 13 ; Nr. 15, no. 13 (2015-07-01), S.7203-7216 |
| Datensatznummer |
250119867
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| Publikation (Nr.) |
 copernicus.org/acp-15-7203-2015.pdf |
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| Zusammenfassung |
| We present the results of laboratory measurements of the ion–ion
recombination coefficient at different temperatures, relative humidities and
concentrations of ozone and sulfur dioxide. The experiments were carried out
using the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at CERN, the walls
of which are made of conductive material, making it possible to measure small
ions. We produced ions in the chamber using a 3.5 GeV c−1 beam of
positively charged pions (π+) generated by the CERN Proton Synchrotron
(PS). When the PS was switched off, galactic cosmic rays were the only
ionization source in the chamber. The range of the ion production rate varied
from 2 to 100 cm−3 s−1, covering the typical range of ionization
throughout the troposphere. The temperature ranged from −55 to
20 °C, the relative humidity (RH) from 0 to 70 %, the SO2
concentration from 0 to 40 ppb, and the ozone concentration from 200 to
700 ppb. The best agreement of the retrieved ion–ion recombination
coefficient with the commonly used literature value of
1.6 × 10−6 cm3 s−1 was found at a temperature of
5 °C and a RH of 40 % (1.5 ± 0.6)
× 10−6 cm3 s−1. At 20 °C and 40 % RH, the
retrieved ion–ion recombination coefficient was instead (2.3 ± 0.7)
× 10−6 cm3 s−1. We observed no dependency of the
ion–ion recombination coefficient on ozone concentration and a weak
variation with sulfur dioxide concentration. However, we observed a more than
fourfold increase in the ion–ion recombination coefficient with decreasing
temperature. We compared our results with three different models and found an
overall agreement for temperatures above 0 °C, but a disagreement at
lower temperatures. We observed a strong increase in the recombination
coefficient for decreasing relative humidities, which has not been reported
previously. |
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