ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-3-2043-2003 DRIFTS and Knudsen cell study of the heterogeneous reactivity of SO<sub>2</sub> and NO<sub>2</sub> on mineral dust Ullerstam M. 1 Johnson M. S. 2 Vogt R. 3 Ljungström E. 1 Gothenburg University, Department of Chemistry, SE-41296 Gothenburg, Sweden Copenhagen University, Department of Chemistry, Universitetsparken 5, DK-2100 Copenhagen, Denmark Ford Forschungszentrum GmbH Aachen, Süsterfeldstrasse 200, D-52072 Aachen, Germanyhagen 25 11 2003 3 6 2043 2051 Copyright: © 2003 M. Ullerstam et al. 2003 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://acp.copernicus.org/articles/3/2043/2003/acp-3-2043-2003.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/3/2043/2003/acp-3-2043-2003.pdf

The heterogeneous oxidation of SO<sub>2</sub> by NO<sub>2</sub> on mineral dust was studied using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and a Knudsen cell. This made it possible to characterise, kinetically, both the formation of sulfate and nitrate as surface products and the gas phase loss of the reactive species. The gas phase loss rate was determined to be first order in both SO<sub>2</sub> and NO<sub>2</sub>. From the DRIFTS experiment the uptake coefficient, <font face="Symbol">g</font>, for the formation of sulfate was determined to be of the order of 10<sup>-10</sup> using the BET area as the reactive surface area. No significant formation of sulfate was seen in the absence of NO<sub>2</sub>. The Knudsen cell study gave uptake coefficients of the order of 10<sup>-6</sup> and 10<sup>-7</sup> for SO<sub>2</sub> and NO<sub>2</sub> respectively. There was no significant difference in uptake when SO<sub>2</sub> or NO<sub>2</sub> were introduced individually compared to experiments in which SO<sub>2</sub> and NO<sub>2</sub> were present at the same time.