Atmos. Chem. Phys. Discuss., 4, 1311-1337, 2004
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Uptake study of ClONO2 and BrONO2 by water droplets
G. Deiber1, Ch. George2, S. Le Calvé1, F. Schweitzer1, and Ph. Mirabel1
1Centre de Géochimie de la Surface/UMR 7517, CNRS and Université Louis Pasteur, 1 rue Blessig, F-67084 Strasbourg, France
2Laboratoire d’Application de la Chimie à l’Environnement (LACE), 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne, France

Abstract. The uptake kinetics of gaseous ClONO2 and BrONO2 on aqueous surfaces were measured, using the droplet train technique coupled to a mass spectrometer, as a function of temperature and liquid composition (pure water and NaCl or NaBr containing solutions). The uptake kinetics are driven by the reactivity of these gases and, for both compounds, the uptake rates on pure water or on NaCl solutions (0.1 M) are comparable. The uptake coefficient γ of ClONO2 does not depend on the temperature while that of BrONO2 increases slightly when the temperature is raised from 272 to 280 K. For ClONO2 and BrONO2, the uptake rates increase on NaBr-doped droplets, enabling the estimation of the mass accommodation coefficient α. The corresponding values for α are 0.108±0.001 for ClONO2 and 0.063±0.009 for BrONO2.

The reactions of ClONO2 and BrONO2 on NaCl solutions lead, respectively to the formation of Cl2 and BrCl. The uptake of ClONO2 on NaBr solutions generates BrCl as primary product, which in turn can react with NaBr to produce Br2. As expected, the only product of BrONO2 reaction on NaBr solution is Br2.

Citation: Deiber, G., George, Ch., Le Calvé, S., Schweitzer, F., and Mirabel, Ph.: Uptake study of ClONO2 and BrONO2 by water droplets, Atmos. Chem. Phys. Discuss., 4, 1311-1337, doi:10.5194/acpd-4-1311-2004, 2004.
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