COLL 20 |
| A major fraction of atmospheric aerosol particles is composed of high molecular weight water soluble organic compounds which contain polycarboxylic acids and a heterogeneous mixture of structures containing aromatic, phenolic and acidic functional groups. These compounds are known as humic materials (HMs) and referred to in atmospheric chemistry literature as HUmic-Like Substances. We will present detailed study on the hygroscopic properties of HULIS extracted from three different aerosol types: fresh wood burning smoke, aged wood burning smoke and aged air pollution particles and will compare them with those of fulvic acids from aquatic sources (Suwannee River FA, often used as models in laboratory studies) separated into several fractions by molecular weight. Specifically we will discuss how the sub saturation hygroscopic growth and activation into droplets of aerosols composed of these species into cloud droplets depends on physico-chemical parameters such as molecular weight, chemical structure and surface tension. Comparison with model calculations will be presented. Time permitting we will also discuss recent measurements of the density and surface tension behavior of these systems. |
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Environmental Interfaces
8:30 AM-12:00 PM, Sunday, 10 September 2006 Sir Francis Drake -- Empire Room, Oral
Division of Colloid & Surface Chemistry |