Events

Neil Donahue, Carnegie Mellon, will discuss "How Much Does Semi-volatile Matter Matter?"

After 20 odd years of studying secondary organic aerosol formation, we know somewhat less than we did at the beginning; the more we know the more we know we don’t know.  At first SOA was viewed as essentially non volatile, with fractional mass yields of 10-20% for important systems.  However, that was evidently wrong.  Another, self-consistent picture, that almost all of the SOA from canonical reactions like alpha-pinene + ozone was semi-volatile, matched almost all of the available data with only a few nagging puzzles such as oddly slow evaporation standing in the way of nearly complete understanding.  However, there is now a great deal of evidence that for typical conditions about 2/3 of the SOA from alpha-pinene is practically non volatile, while the remaining 1/3 is semi volatile. We shall discuss several different lines of evidence leading to this conclusion, including observations of new-particle formation and growth from the CLOUD experiment at CERN and aerosol population mixing experiments conducted at CMU to explore the rate at which semi-volatile constituents move between different particle populations.  Finally, we shall continue the Sisyphean undertaking of attempting to develop a self-consistent theoretical framework for this “simple” system. 

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