Uptake study of ClONO2 and BrONO2 by Halide containing droplets 1Centre de Gochimie de la Surface / UMR 7517 CNRS and Univ. 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, as a function of temperature and liquid composition
(pure water and NaCl or NaBr containing solutions) using the droplet train
technique coupled to a mass spectrometer. 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 (0.1M) 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 280K. 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±0.033 for ClONO2 and 0.063±0.021 for
BrONO2 where the statistical errors correspond to ±2σ.
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 Halide containing droplets, Atmos. Chem. Phys., 4, 1291-1299, doi:10.5194/acp-4-1291-2004, 2004.