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Films dept seminar abstract fall09

Films dept seminar abstract fall09 - singly as well as in...

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CHEMISTRY Departmental Seminar Annalise Van Wyngarden Organic film formation on atmospheric sulfuric acid particles The stratospheric aerosol layer has traditionally been thought of as being composed of pure sulfuric acid/water aerosols that do not absorb solar UV-vis light, but recent airborne measurements of single particle composition (e.g. Murphy et al. 2007) have shown that 10-20% of sampled aerosols in the lower stratosphere have significant organic content. Since there is very little water vapor in the stratosphere, these sulfuric acid/organic particles will be extremely acidic (40-80 wt% sulfuric acid). Here I show that small amounts (approx. 0.03 M) of carbonyl compounds allowed to react with such concentrated sulfuric acid solutions produce highly-colored solutions that continue to darken for months after mixing. Propanal, methylglyoxal, and glyoxal were examined
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Unformatted text preview: singly as well as in various combinations. In the case of propanal, colored organic films form on the surfaces of the solutions on a timescale of days to weeks depending on acidity. If colored solutions, films, and precipitates exist in aerosols in the lower stratosphere (or upper troposphere) in significant quantities they would alter the climate effects of the aerosols. They could even impact satellite retrievals of atmospheric species that employ UV-vis wavelengths. The chemical mechanism(s) for these results must be understood in order to evaluate whether or not they will be important in stratospheric aerosols, so future work on chemical characterization of these solutions will also be discussed. Tuesday, September 8, 2009, 4:30 PM Duncan Hall 135 For more information: email or phone Prof. Annalise Van Wyngarden at 408-924-5282 [email protected]
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