Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt%). However, recent airborne measurements have shown that these particles may also contain a significant fraction of organic compounds (Murphy et al. 2007). Experiments combining small amounts of organics (glyoxal, methylglyoxal and/or propanal) with sulfuric acid at concentrations typical of UT/LS aerosols produced highly colored solutions, precipitates, and even surface films that have the potential to impact chemical, optical and/or cloud-forming properties of aerosols. Surface films may control these aerosol properties, so film formation rates were examined to determine the effects of organic mixture, acidity, temperature and exposure to light.  The chemical composition of the films and solutions were studied by various analytical techniques, including tandem mass spectrometry and Attenuated Total Reflectance-FTIR and UV-Vis spectroscopies. Results will be used to assess whether such films could impact aerosol chemistry or climate properties.

Colored solutes, precipitates and surface films produced by reactions of organics in sulfuric acid solutions at upper troposphere/lower stratosphere aerosol acidities

243rd National Meeting (2012)

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