AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Laboratory Characterization of a Size-Resolved CPC Battery to Infer the Composition of Freshly Formed Atmospheric Nuclei
CHONGAI KUANG, Juha Kangasluoma, Daniela Wimmer, Katrianne Lehtipalo, Jian Wang, Markku Kulmala, Tuukka Petäjä, Brookhaven National Laboratory
Abstract Number: 357 Working Group: Instrumentation and Methods
Abstract Atmospheric particle nucleation is an important environmental nano-scale process, with climate models indicating that nearly half of the global cloud condensation nuclei (CCN) may be formed from freshly nucleated particles. However, our understanding of atmospheric nucleation and its influence on climate is limited since few direct measurements have been made of either the nucleation rate or the chemical composition of the freshly formed clusters. In this study, we have developed an instrument to infer the size-resolved composition of freshly formed atmospheric particles, addressing a key knowledge gap in the composition of nucleated aerosol below 3 nanometers. This size-resolved condensation particle counter battery (SR-CPCb) is composed of a nanoparticle mobility spectrometer that has been optimized for the sampling and mobility classification of sub 3 nanometer particles. By sampling mobility-classified particles, the SR-CPCb accounts for the strong dependence of CPC detection on particle size and charge below 2 nanometers. Any measured differences in CPC response can then be attributed to composition-specific interactions between the particle and the various working fluids. The CPCb utilizes the following CPCs with their accompanying working fluids: a Particle Size Magnifier (diethylene glycol), a DEG-UCPC (diethylene glycol), a TSI 3786 UCPC (water), and a TSI 3025A UCPC (butanol). The following methods were used to generate challenge aerosols for the CPCb characterization: (1) electrospray generation of molecular ion mobility standards, (2) evaporation of solid sodium chloride via tube furnace, (3) evaporation of solid ammonium sulfate via tube furnace, (4) tungsten oxide formation via a wire generator, (5) candle aerosol generation, (6) limonene ozonolysis in a flow tube reactor, and (7) electrospray generation of sucrose. Presented results will include the particle composition dependent response of the SR-CPCb.