Measured Organic Particle Types with Molecular Modeling of their Volatility and Uptake Properties

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This research presents a combined measurement, analysis, and modeling approach that addresses these uncertainties in three related tasks. The Principal Investigator (PI) will: (1) collect and analyze organic aerosols generated in smog chambers for functional group composition and morphology (including chemical distribution within individual particles) using Scanning Transmission X-ray Microscopy (STXM) and Fourier Transform Infrared Spectroscopy (FTIR), as a function of "age" (oxidant exposure); (2) analyze the morphology of our archive of approximately 1000 ambient particle spectra collected during eleven field campaigns in comparison to the smog chamber particles and other published particle types; and (3) identify the links between the observed organic compound types and morphologies via model simulations. For each type, the PI will also calculate the volatility and water uptake properties that these particles exhibit in atmospheric conditions. Given the wide range of atmospheric particle sizes of interest and the computational limitations of simulating individual molecules, the work will include "full particle" techniques for particles smaller than 20 nanometers and "slab" techniques for estimating parameters suitable for describing larger particles in atmospheric models.This project creates a set of training opportunities for two postdoctoral scholars and one graduate student who will participate in the scientific enterprise through engagement in experimental and computational methods. The work establishes a new collaboration among three U.S. academic institutions. In addition, the PI will involve students in summarizing our recent findings on aerosol behavior for a broader audience for posting on the "Outreach" web page maintained by the investigators.