Kinetics and mechanism of the uptake of N2O5 on mineral dust at 298 K S. Seisel1, C. Börensen2, R. Vogt2, and R. Zellner1 1Institute for Physical and Theoretical Chemistry, University of Duisburg-Essen, Germany 2Ford Forschungszentrum Aachen, Aachen, Germany
Abstract. The heterogeneous reaction of N2O5 with mineral (Saharan) dust has
been studied at T=298 K using a combination of Knudsen and DRIFTS cells for
kinetic and product investigations, respectively. The initial uptake
coefficient has been determined to be γ=(8.0±0.3)·10−2. This uptake slowly saturates into a steady state uptake of
γ=(1.3±0.3)·10−2 suggesting that reaction of
N2O5 with the mineral dust surface and hydrolysis of
N2O5 on the surface take place simultaneously. Both uptake
coefficients have been calculated on the basis of the geometric (projected)
surface area of the sample and must therefore be regarded as upper limits.
In addition, the product investigations show that N2O5 is
irreversibly taken up to form nitrate on the surface. Recent model
calculations suggest that the uptake rates of N2O5 on Saharan dust
which we measured may be large enough to influence the photo-oxidant budget of the
Citation: Seisel, S., Börensen, C., Vogt, R., and Zellner, R.: Kinetics and mechanism of the uptake of N2O5 on mineral dust at 298 K, Atmos. Chem. Phys., 5, 3423-3432, doi:10.5194/acp-5-3423-2005, 2005.