Despite the chirality of many biogenic and anthropogenic organic atmospheric constituents, the role of stereochemistry in the formation and transformation of secondary organic aerosols and clouds has not been evaluated. Motivated by recent reports of region-specific chiral signatures that suggest a unique climate nexus between the atmosphere and the biosphere, we hypothesize that atmospheric stereochemistry could lead to fundamentally different secondary aerosol and cloud formation mechanisms depending on geographic location in the world. We present results from highly sensitive, coherent vibrational spectroscopic studies of laboratory models systems and field-collected aerosol particles. Specifically, sum frequency generation (SFG) spectra of synthetic aerosol particles collected on Teflon filters at the Harvard Environmental Chamber show clear vibrational and chiral signatures. SFG and second harmonic generation microscopy of size-resolved natural particles collected in the central Amazonian Basin allow us to decipher the role that size plays in determining the chiral properties of particles. SFG spectra of particles collected in Blodgett Forest, California and Hyyti�l�, Finland also show vibrational and chiral signatures. Using back-trajectories and aerosol mass spectrometry, the chirality information is correlated to the origin and chemical composition of the aerosols.

Chirality in climate change

242nd National Meeting (2011)

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