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Formation of different photolytic precursors of atomic Cl from pure and contaminated NACl aerosol

: Zetzsch, C.; Scheer, V.; Behnke, W.; Krüger, H.-U.

Restelli, G.; Angeletti, G.:
Physico-chemical behaviour of atmospheric pollutants. Proceedings of the 6th European Symposium. Vol.2
Luxembourg: Office for Official Publications of the European Communities, 1994 (Air pollution research report)
ISBN: 92-826-4120-1
European Symposium on Physico-Chemical Behaviour of Atmospheric Pollutants <6, 1993, Varese>
Fraunhofer ITA ( ITEM) ()
aerosol; air pollution; atmospheric chemistry; OH radical; photochemical degradation; photochemistry; physical chemistry; sea spray; smog chamber; theoretical chemistry

The uptake of N2O5 by wet, deliquescent NaCl aerosol is investigated, and the uptake coefficient, gamma, is obtained to be 0.032 +- 0.003. Two different reaction pathways occur after the uptake: a) reaction with the chloride ion to form ClNO2, b) reaction with H2O to form 2HNO3. At high NaCl concentrations above 2 mol/l typical of the aerosol the ratio of the second order rate constants ka/kb was determined in teflon bag experiments and between 0.02 and 6 mol/l with a wetted-wall flowtube technique. Both methods lead within the error to the same ration ka/kb = 60. Employing the wetted-wall flowtube apparatus below 2 mol/l of NaCl, the ratio was observed to increase drastically with decreasing Cl(-)-concentration, reaching a value of about 500 at 0.01 mol/l. On the other hand, the addition of 0.3 mol/l of Na2SO4 causes the ratio of ka/kb to remain below 100 (abstract truncated).