AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Particle Formation from Methanesulfonic Acid and Ammonia/Amines via Laboratory Experiments, Ab Initio Calculations, and Modeling Studies
HAIHAN CHEN, Mychel E. Varner, Andrew Martinez, Veronique Perraud, Micheal, J. Ezell, Kristine Arquero, Jeremy Horne, Benny Gerber, Donald Dabdub, Barbara J. Finlayson-Pitts, University of California, Irvine
Abstract Number: 69 Working Group: Advances in the Physics and Chemistry of New Particle Formation and Growth
Abstract New particle formation is frequently observed in the tropospheric boundary layer. It accounts for up to half of global cloud condensation nuclei. Therefore, understanding new particle formation from gaseous precursors is critical in reducing the current uncertainties associated with climate-aerosol interaction. While sulfuric acid reacting with ammonia/amines has been well established as the main nucleating pathway, recent field and laboratory studies suggest that other gas precursors may contribute. These additional precursors include methanesulfonic acid from the oxidation of organosulfur compounds that are generated from biological processes over oceans as well as agricultural and domestic activities. In this study, laboratory experiments are performed in a borosilicate glass flow reactor to investigate particle formation from methanesulfonic acid and ammonia/amines. The relative effectiveness of particle formation from ammonia, methylamine, dimethylamine, and trimethylamine with methanesulfonic acid and the dependence on precursor concentrations and relative humidity are reported. In parallel, quantum chemical calculations are performed to provide insights on initial clusters and processes leading to particle formation. Calculations show that the observed effects of gas precursors and relative humidity on particle formation are related to the structures and stabilities of initial clusters. The nucleating pathway is further implemented in a three dimensional airshed model in the South Coast Air Basin of California to evaluate emissions of methanesulfonic acid and ammonia/amines and their contributions to particle formation.