HR: 09:30h
AN: A41G-06    [Abstracts]
TI: Direct Experimental Evidence for a Heterogeneous Reaction of Ozone With Bromide at the Air- Aqueous Interface
AU: Clifford, D
EM: dcliffor@chem.utoronto.ca
AF: Department of Chemistry, University of Toronto, 80 St George St, Toronto, ON M5S 3H6, Canada
AU: * Donaldson, J
EM: jdonalds@chem.utoronto.ca
AF: Department of Chemistry, University of Toronto, 80 St George St, Toronto, ON M5S 3H6, Canada
AB: An order of magnitude discrepancy between measured and predicted Br2 production in the reaction of ozone with deliquesced NaBr aerosol, combined with recent experimental and theoretical work indicating an enhancement of bromide anions at the air-aqueous interface have led to the suggestion that an interface reaction occurs between ozone and bromide. We have used an interface-sensitive fluorescent probe to measure pH changes associated with the interfacial reaction of ozone and bromide. The rate of pH change is well described by a Langmuir-Hinshelwood surface-mediated kinetic model. When octanol is present at the interface, the rate of pH change tracks the octanol adsorption isotherm, as expected if octanol enhances the concentration of ozone at the surface, as is known from previous work. These observations constitute direct evidence for a surface reaction between ozone and bromide anions.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting