Atmospheric Chemistry Program Seminar
Molecules to particles – Experiments and simulations relevant to new particle formation in the marine atmosphere by Henning Finkenzeller, CU Boulder, ANYL 4th year, Volkamer lab
"In this talk, I present my projects within the CLOUD consortium. CLOUD is an atmospheric simulation chamber at CERN, Geneva, Switzerland, to study the formation and growth of new particles in urban, rural, marine, and free tropospheric environments. In particular, iodic acid (HIO3) is thought to be a key precursor for new particle formation in the marine atmosphere, but the sources of HIO3 are currently unknown. Condensation of HIO3 is thought to be the primary mechanism by which iodine forms new particles at Mace Head, Ireland, and possibly other marine environments (Sipilä et al., 2016).
I have adapted the Volkamer group iodine chemistry box model to investigate known sources of HIO3 (e.g., OIO + OH) and inform missing formation pathways. In combination with theory, I have incorporated new gas-phase reactions into the model, and compared the predictions with CLOUD observations. As pre-requisite for modeling CLOUD experiments, I have developed the photolysis module (irradiation by different lamps), temperature and humidity control, the injection of precursor gases, dilution and losses to the wall. The experimental conditions (precursor and intermediate species concentrations) can be prescribed, or taken as those observed in the chamber.
I have further developed the Model for Acid Base Chemistry and Nanoparticle Growth (MABNAG) to represent reactive uptake due to Setschenow salting-in of glyoxal (CHOCHO). Glyoxal is a volatile, ubiquitous, and putatively simple gas that forms from the oxidation of aromatic hydrocarbons, isoprene, and also non-traditional precursors, e.g., fatty acids. Upon contact with wet and sulfate containing particles glyoxal-hydrate-sulfate complexes form that have extremely low volatility. I am examining the contributions to the later stages of particle growth, and am developing a glyoxal source for future experiments at CLOUD."
*Due to the closure of the campus Papa John's, lunch will be from Subway*