ASD Seminar

Biogenic sources as well as human activities contribute large amounts of volatile organic compounds to the atmosphere. Upon oxidation, polyfunctional molecules such as dicarboxylic acids are formed. These molecules generally have lower vapor pressures than the parent molecules and are able to condense on existing particles or maybe even participate in formation of new particles in the atmosphere. 


Current knowledge about the thermodynamic properties governing this partitioning as well as the influence of the organic molecules on properties of aqueous solution droplets is poor. We have therefore developed new methods based on the HTDMA and EDB (Hygroscopicity Tandem Differential Mobility Analyzer, electrodynamic balance) techniques for determining the subcooled liquid state and solid state vapor pressure as well as other thermodynamic properties of secondary organic aerosol components. We have recently measured evaporation rates of crystals [1] and aqueous solution droplets containing one dicarboxylic acid (C3 to C5) and water [2-3-4]. We are currently expanding the list of organics and investigate more complicated systems such as mixed inorganic/ organic particles.