AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Neutral Sulfuric Acid Clusters during Strong Nucleation Events in a Sulfate-Rich Urban Atmosphere
JUN ZHAO, Fred Eisele, Peter McMurry, James N. Smith, University of Minnesota
Abstract Number: 634 Working Group: Aerosol Nucleation: From Clusters to Nanoparticles
Abstract New particle formation (NPF) in the polluted boundary layer arises from the clustering of electrically neutral compounds. Newly formed particles may affect concentrations of cloud condensation nuclei (CCN), thereby affecting cloud formation and global climate, so it is important to understand NPF when modeling climate. During the summer of 2009, we carried out measurements in Atlanta, GA, at a site that was frequently impacted by plumes from nearby coal-fired power plants. Measurements included concentrations of nucleating vapors, clusters formed by nucleation obtained with a specially-designed chemical ionization mass spectrometer and particle number distributions down to 1 nm (Jiang et al., 2011). This work will describe measurements of neutral molecular clusters obtained with the Cluster Chemical Ionization Mass Spectrometer (the Cluster CIMS). The concentrations of neutral sulfuric acid-containing clusters are obtained by accounting for the ion-induced clustering process in the sampling inlet, after subtracting background signals. We found that background signals for clusters correlate with temporal variations of malonic acid (mw=104), and we therefore used malonic acid as a tracer for background signals at cluster m/z values.
J. Jiang, J. Zhao, M. Chen, J. Scheckman, B. J. Williams, F. L. Eisele, and P. H. McMurry. First measurements of atmospheric cluster and 1-2 nm particle number distribution functions during nucleation events. Aerosol Science & Technology, 45(4), II-V (2011)