Title Spectroscopic studies of the heterogeneous reaction between O3(g) and halides at the surface of frozen salt solutions
Author Wren, S.N.; Kahan, T.F.; Jumaa, K.B.; Donaldson, D.J.
Author Affil Wren, S.N., University of Toronto, Department of Chemistry, Toronto, ON, Canada. Other: , Canada
Source Journal of Geophysical Research, 115(D16), Citation D16309. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148- 0227
Publication Date 2010
Notes In English. 36 refs. GeoRef Acc. No: 310416
Index Terms atmospheric boundary layer; boundary layer; freezing; ice; ozone; spectra; atmosphere; autocatalytic cycle; bromine; bromine explosion; frozen salt solutions; gaseous phase; halides; halogens; heterogeneity; laser-induced fluorescence; Raman spectra; sea ice; seasonal variations; solution; surface features; troposphere
Abstract Springtime ozone depletion events have been linked to elevated levels of bromine in the polar boundary layer. It has also been suggested that iodine may play an important role in boundary layer chemistry. However, the mechanism(s) for initial halogen activation is not well understood. We report results of experiments using glancing-angle laser-induced fluorescence (LIF) and glancing- angle Raman spectroscopy to investigate the heterogeneous reaction of gas-phase ozone with bromide and iodide ions at the surface of frozen salt solutions. The results suggest that halides that have been excluded to the ice surface during the freezing process react in the dark and under non-acidified conditions to produce molecular halogen species. At environmentally relevant bromide concentrations, the reaction proceeds ~60 times more rapidly at ice surfaces than at the surface of aqueous solutions. At an ozone concentration of ~8 1015 molec cm-3, and sea water concentrations of bromide and iodide, we estimate uptake coefficients gamma (Br-) = (1.3 0.5) 10-8 and gamma (I-) = (1.6 0.5) 10-9. We estimate that at atmospheric ozone concentrations, the uptake coefficients will be approximately a factor of ten greater.
URL http://hdl.handle.net/10.1029/2010JD013929
Publication Type journal article
Record ID 65007181