HR: 0830h
AN: A51F-0739    [PDF]
TI: Real Time Measurements of Oxidation of SAMs using ATR-FTIR; Kinetics and Reaction Probabilities
AU: * Dubowski, Y
EM: yael@uci.edu
AF: University of California, Irvine, Department of Chemistry, Irvine, CA 92697-2025
AU: Finlayson-Pitts, B J
EM: bjfinlay@uci.edu
AF: University of California, Irvine, Department of Chemistry, Irvine, CA 92697-2025
AB: Most studies of heterogeneous reactions on aerosols have focused on their implications for gas phase species. Less attention, however, has been given to the modification of aerosol surfaces during such reactions. Alteration of aerosol surface species may affect their hygroscopic and radiative properties as well as their reactivity toward other atmospheric trace species. In the present study, we use self-assembled organic monolayers (SAM) as proxies for atmospheric organic aerosols. Detection of even very short carbon chains (i.e., C3) as well as continuous monitoring of the SAMs during the experiments are achieved by depositing the SAMs directly on a silicon attenuated total reflection (ATR) crystal (10 reflections) attached to a FTIR. The oxidation kinetics of unsaturated SAMs by ozone and hydroxyl radicals are studied using this technique, as a function of carbon chain length and surface roughness (using mixed SAMs with different length). Reaction probabilities are calculated based on surface oxidation and compared to probabilities previously calculated by gas phase monitoring. The atmospheric implications will be discussed.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting