The enhanced greenhouse effect is currently considered to be our most important global environmental problem. While the magnitude of radiation absorbed by greenhouse gases is known to a high certainty, the absorption of radiation by atmospheric aerosol particles is not. In the initial Visiting Faculty Program application, we proposed the use of an ultraviolet-visible (UV/Vis) spectrometer equipped with a liquid waveguide capillary flow cell to determine the extent to which secondary organic aerosol particles (SOA) absorb visible light. Early in the research period, the UV/Vis technique was optimized for three solvent systems (methanol, water and 0.1 M hydrochloric acid). Using the optimized UV/Vis technique optical properties such as mass specific absorption cross-section and imaginary refractive index were determined for SOA dissolved in different solvent systems. The end result of the UV/Vis studies is the inclusion of SOA optical properties into climate models developed at the Pacific Northwest National Laboratory (PNNL). This knowledge will help to improve climate models, which currently do not include the effect of SOA. We also utilized Fourier Transform Infrared Spectroscopy to help elucidate the chemical composition of SOA. Finally, an experimental method was developed to determine the peroxide content of SOA. It is expected that these studies will connect the chemical composition of SOA to their optical properties. The research carried out at PNNL will be included in two undergraduate senior theses at Concordia University - Portland (CU). It is also expected that this research will be included in a peer-reviewed journal article. It is our hope that success of our work will result in future collaborations between PNNL and CU students.
Wise, Matthew E.; Shilling, John; Imholt, Felisha; and Caylor, Ryan, "Determination of the Optical Properties of Secondary Organic Aerosol Particles" (2015). Faculty Research. 2.