The interface between an aerosol gas phase and its particle phase has now emerged as a major region of interest for environmental molecular chemistry, yet it is this interface that is notoriously difficult to access experimentally. We demonstrate how vibrational sum frequency generation (SFG), a coherent surface sensitive spectroscopy, provides compositional, structural and orientational information about organic components of aerosol particle surfaces with minimal sample manipulation. We analyze surfaces of secondary organic aerosol particles prepared from ozonolysis of a-pinene, atmospherically relevant volatile organic compound, in time periods of minutes to hours in a flow tube constructed at Harvard. Following spectroscopic analysis, we determine the limit of detection of the intensity of the SFG response as a function of particle mass. Filter substrates with nanogram amounts of material provide sufficient SFG signal intensity for detection, which indicates the utility of SFG to analyze particle samples with high time resolution.

Analysis of secondary organic aerosol particle surfaces using vibrational spectroscopy

245th National Meeting (2013)

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