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- Title
Experimental investigation of ion-ion recombination at atmospheric conditions.
- Authors
Franchin, A.; Ehrhart, S.; Leppä, J.; Nieminen, T.; Gagné, S.; Schobesberger, S.; Wimmer, D.; Duplissy, J.; Riccobono, F.; Dunne, E.; Rondo, L.; Downard, A.; Bianchi, F.; Kupc, A.; Tsagkogeorgas, G.; Lehtipalo, K.; Manninen, H. E.; Almeida, J.; Amorim, A.; Wagner, P. E.
- Abstract
We present the results of laboratory measurements of the ion-ion recombination coeffcient at different temperatures, relative humidities and concentrations of ozone and sulfur dioxide. The experiments were carried out using the Cosmics Leaving OUtdoor 5 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 3.5GeVc-1 beam of positively-charged pions (π+) from the CERN Proton Synchrotron (PS) and with galactic cosmic rays, when the PS was switched off. The range of the ion production rate varied from 2 to 100 cm-3 s-1, covering the typical range of 10 ionization throughout the troposphere. The temperature ranged from -55 to 20 °C, the relative humidity from 0 to 70 %, the SO2 concentration from 0 to 40 ppb, and the ozone concentration from 200 to 700 ppb. At 20 °C and 40% RH, the retrieved ion-ion recombination coeffcient was (2.3±0.7) ×10-6 cm3 s-1. We observed no dependency of the ion-ion recombination coeffcient on ozone concentration and a weak variation with 15 sulfur dioxide concentration. However, we found a strong dependency of the ion-ion recombination coeffcient on 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 dependency of the recombination coeffcient on relative humidity, which has not been reported previously.
- Subjects
ION-ion collisions; HUMIDITY; OZONE; SULFUR dioxide; CLOUD droplets; PROTON synchrotrons; COSMIC rays
- Publication
Atmospheric Chemistry & Physics Discussions, 2015, Vol 15, Issue 3, p3667
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/acpd-15-3667-2015