Humidity Influence on NO2 Uptake by Solid Sea Salts Contribution to subproject CMD

Matrix isolation combined with ESR (MIESR) technique and mass spectrometry (MS) were used to study NO2 uptake on NaCl crystallites deposited from a water solution. HCl was found to be the main product. Rates of heterogeneous NO2 losses and HCl formation were measured under "dry " ([H2O]»2´1012 cm-3) and "humidified " {[H2O] = (1014-2´1016) cm-3}. The [NO2] was changed from 1010 to 5´1013 cm-3. A general kinetic mechanism including adsorption, desorption and surface reaction is proposed to explain our results as well as the results of (Vogt and Finlayson-Pitts, 1995) for NO2 uptake on a crystal powder. The NO2 uptake coefficient is extrapolated to real tropospheric conditions using the kinetic mechanism and the rate constants of elementary steps obtained