Surface properties of organic aerosol are poorly constrained, due to the complex nature of their formation and atmospheric aging, as well as due to the practical challenges associated with gaining surface-specific information. However, a better description of the interfacial behaviour of atmospheric organics is critical to understanding the role that organic aerosol plays in influencing climate, human health and air quality.  This talk will highlight recent studies of the surface behaviour of atmospherically important oxygen-containing organic molecules in aqueous solutions of relevant composition. Specifically, we demonstrate that molecular structure, pH, and the presence and identity of additional salts, strongly impact the surface adsorption of low-molecular-weight dicarboxylic acids (i.e., malonic, glutaric, and adipic acid) and ketones (i.e., 3-pentanone); structure and aqueous composition play an important, yet somewhat different role in governing the surface adsorption of a-dicarbonyl organic compounds (i.e., methylglyoxal). Significantly, we show that a combined experimental and theoretical approach involving vibrational sum frequency generation spectroscopy (VSFS), surface tensiometry, bulk vibrational spectroscopies, molecular dynamics simulations, and density functional theory calculations, is essential for obtaining a detailed molecular picture of the adsorptive properties of these fundamentally important atmospheric organics.

Combining experiment and theory: Atmospheric organics at the air-water interface

248th National Meeting (2014)

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