American Association for Aerosol Research - Abstract Submission

AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA

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Spectro-microscopic Characterization of Physical Properties and Phase Separations in Individual Atmospheric Particles

RACHEL O'BRIEN, Bingbing Wang, Steven Kelly, Nils Lundt, Scott A. Epstein, Amanda MacMillan, Yuan You, Alexander Laskin, Sergey Nizkorodov, Allan Bertram, Ryan Moffet, Mary Gilles, LBNL and University of the Pacific

     Abstract Number: 583
     Working Group: Aerosol Chemistry

Abstract
The phase state and liquid-liquid phase separations of ambient and laboratory generated aerosol particles were investigated using (1) scanning transmission x-ray microscopy/near-edge x-ray absorption fine structure spectroscopy (STXM/NEXAFS) coupled to a relative humidity (RH) controlled in-situ chamber and (2) environmental scanning electron microscopy (ESEM). The phase states of the particles were determined from measurements of their size and optical density. A comparison is made between the observed phase states of ambient samples and of laboratory generated aerosols to determine how well laboratory samples represent the phase of ambient samples. In addition, liquid-liquid phase separations in laboratory generated particles were investigated. Preliminary results showing that liquid-liquid phase separations occur at RH’s between the deliquescence and efflorescence points and that the organic phase surrounds the inorganic phase will be presented. The STXM/NEXAFS technique provides insight into the degree of mixing at the deliquescence point and the degree of phase separation for particles of atmospherically relevant sizes.