HR: 0800h
AN: A51C-0595    [Abstracts]
TI: A Study of Reactive Halogen Release From Frozen Sodium Halide Solutions: The Effect of Photons and Hydroxyl Radicals
AU: * Sjostedt, S J
EM: ssjosted@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry Lash Miller Chemical Laboratories 80 St. George Street, Toronto, ON M5S 3H6, Canada
AU: Symington, A
EM: ams85@cam.ac.uk
AF: University of Cambridge, University of Cambridge University Chemical Laboratory Lensfield Rd, Cambridge, CB2 1EW, United Kingdom
AU: Abbatt, J P
EM: jabbatt@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry Lash Miller Chemical Laboratories 80 St. George Street, Toronto, ON M5S 3H6, Canada
AB: It has been established that reactive halogen species are instrumental in ozone depletion events observed at high latitudes. Recent field campaigns also indicate that in other environments, such as the marine boundary layer, halogens influence the oxidizing potential, either by directly oxidizing reduced species or by cycling HO₂ to OH. Gas phase chemistry has been unable to account for the amount of reactive halogens observed during field campaigns. Heterogeneous autocatalytic mechanisms, such as the bromine explosion, have been invoked to help balance the ledgers. Still the initial release of reactive halogens remains an open question. In our study we explore the role of photons and gas phase hydroxyl radicals as potential oxidants of halide species frozen in solution. Depending on the reactant required, either a xenon arc lamp (photons) or microwave plasma (OH) was employed to generate the oxidizing species. In the case of photons, the pathway for oxidant formation was via dissolved nitrate photolysis. A chemical ionization mass spectrometer was subsequently used to detect the gas phase halogen species liberated from the substrate. We see the effects of temperature, halide concentration, pH, and nitrate concentration within the frozen solution upon the halogen yield.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting