ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-4-2083-2004 Enhanced uptake of water by oxidatively processed oleic acid Asad A. 1 Mmereki B. T. 1 Donaldson D. J. 1 Department of Chemistry and Department of Physical and Environmental Sciences, University of Toronto, 80 St. George St., Toronto, Ont. M5S 3H6, Canada 19 10 2005 4 8 2083 2089 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/4/2083/2004/acp-4-2083-2004.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/4/2083/2004/acp-4-2083-2004.pdf

A quartz crystal microbalance apparatus has been used to measure the room temperature uptake of water vapour by thin films of oleic acid as a function of relative humidity, both before and following exposure of the films to various partial pressures of gas phase ozone. A rapid increase in the water-sorbing ability of the film is observed as its exposure to ozone is increased, followed by a plateau region in which additional water is taken up more gradually. In this fully-processed region the mass of water taken up by the film is about 4 times that of the unprocessed film. Infrared spectra of the films, measured after variable exposures to ozone, show dramatic increases in both the "free" and hydrogen-bonded O-H stretching regions, and a decrease in the intensity of olefinic features. These results are consistent with the formation of an oxygenated polymeric product or products, as well as the gas phase products previously identified.