AVS 56th International Symposium & Exhibition
    Surface Science Thursday Sessions
       Session SS-ThP

Paper SS-ThP16
Surface Reaction of Ozone with Alkali Halide Salts

Thursday, November 12, 2009, 6:00 pm, Room Hall 3

Session: Surface Science Poster Session
Presenter: T. McIntire, University of California, Irvine
Authors: T. McIntire, University of California, Irvine
J. Taing, University of California, Irvine
P. Ashby, Lawrence Berkeley National Laboratory
R.L. Grimm, University of California, Irvine
A. Margarella, University of California, Irvine
M.H. Cheng, University of California, Irvine
Z. Liu, Lawrence Berkeley National Laboratory
J.C. Hemminger, University of California, Irvine
Correspondent: Click to Email
Heterogeneous reactions involving the oxidation of the halide components of sea-salt aerosols with trace atmospheric gases (e.g., ozone, hydroxyl, and NOx) have been proposed to be responsible for the release of active halogen species into the gas phase. While such halogen containing species have been observed in the marine boundary layer by field studies, the detailed mechanisms of the heterogeneous reactions leading to halogen release from sea salt aerosols are not well understood. In this work, reactions of gas phase ozone with alkali halide single crystals were studied at varying ozone and water vapor concentrations. Changes in the alkali halide salts were measured using transmission FTIR, x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). While previous investigations found single crystals of KI oxidize to form a passivating layer of KIO3 crystallites, the present study notes the loss of reactants with no observed surface-phase oxidized species, AFM experiments show that ozonolysis of KBr single crystals leads to roughening of step edges and the formation of etch pits which appears to depend on the amount of water vapor present. XPS spectra show a decrease in interfacial bromide believed to be concomitant with the etching observed in the AFM studies. Implications for the role of water on the reaction of gases such as ozone with alkali halide single crystals are discussed.