HR: 15:05h
AN: A43F-06    [Abstracts]
TI: Laboratory Studies of the Atmospheric Chemistry of Ice: Roles of Surface Disorder and Morphology
AU: * McNeill, V
EM: vfmcneill@columbia.edu
AF: Columbia University, Department of Chemical Engineering, New York, NY 10027, United States
AB: We will present an overview of our recent laboratory work on the surface chemistry of ice under a wide range of conditions relevant to atmospheric chemistry. The results of these studies provide new information on the complex dependence of the trace gas-ice interaction on the surface roughness, grain size, and surface disordering of the substrate. Using the surface-specific technique ellipsometry, we demonstrated that trace, atmospherically relevant quantities of hydrogen chloride (HCl) can induce surface disorder on ice at temperatures as low as -80°C. We then investigated the effects of surface disorder on the heterogeneous chemistry of ice by using a low- temperature coated-wall flow tube reactor with chemical ionization mass spectrometry (CIMS) detection of the gas phase composition. We found that surface disorder enhances the reaction of HCl with chlorine nitrate on ice, and is necessary to explain the levels of chlorine activation observed during PSC events. Additionally, we found that the affinity of acetic acid for the ice surface increases in the presence of surface disorder. We also explored the effect of ice morphology on ice-trace gas interactions using the coated wall flow tube-CIMS technique. We investigated the interaction of HCl with three different ice substrates, which allowed us to observe the effects of surface roughness and domain size at a range of conditions corresponding to three unique surface states. Perspective will be given on the role of surface disordering on ice in the atmospheric chemistry of snow in polar regions.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting