AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Exploring the Physical and Chemical Properties of Aerosol Using Aerosol Optical Tweezers
JAMES F. DAVIES, Kevin Wilson, Lawrence Berkeley National Laboratory
Abstract Number: 23 Working Group: Aerosol Chemistry
Abstract The use of single particle methods in the analysis of aerosol allows for an exploration of their microscopic physical and chemical properties in the absence of complicating particle-particle and particle-surface interactions. For instance, precise information on the hygroscopicity, viscosity, vapor pressure, freezing, and surface tension of aerosol may be derived from measurements on aerosol droplets made using optical tweezers.
Using the newly developed Aerosol Optical Tweezers (Biral AOT100), we demonstrate the expansive capabilities of the technique for exploring heterogeneous oxidation and photo-chemistry of model aerosol and flow-tube derived SOA. Confining and reacting particles over long time periods allows progressive changes in the particle radius to be resolved over the course of reaction, from which changes in hygroscopicity and mass may be inferred.
Specifically, we address a gap in the field of aerosol science relating to the use of single particle methods for the investigation of OH-initiated oxidation chemistry. Using chemical and photo-chemical pathways, we generate hydroxyl radical in-situ in the AOT trapping chamber and monitor the course of the reaction of organic aerosol over timescales inaccessible to flow-based techniques. Furthermore, we explore new methods for chemical analysis of optically confined droplets in order to better understand their developing composition during reaction.