We analyze natural secondary organic particle samples collected from a tropical and boreal forest, as well as marine particles collected in the UCSD wave chamber. Here, we show how the chemical identity of the aerosol particle phase sampled there can be evaluated directly and without the need for solid phase extraction, reconstitution, or other sample manipulation with a table-top laser spectroscopic method that probes sub-nanogram amounts of particle material collected on impactor and filter substrates. The particles are studied using vibrational sum frequency generation (SFG) and second harmonic generation (SHG) imaging microscopy, followed by comparison to SFG and SHG responses obtained from synthetic organic aerosol particles prepared at the Harvard Environmental Chamber and to hydrocarbon reference compounds. We assess how the stereochemistry of the gas-phase molecular precursors impacts the secondary organic aerosol particles that form from them. The exquisite sensitivity of SFG and SHG imaging to environments where symmetry is broken make these techniques well-suited to carry out this analysis.

Coherent vibrational spectroscopy and electronic imaging for contrasting secondary organic aerosol particles from various sources

243rd National Meeting (2012)

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