AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Rapid Measurement of Particle Hygroscopicity
TAMARA PINTERICH, Steven Spielman, Susanne Hering, Jian Wang, Brookhaven National Laboratory
Abstract Number: 438 Working Group: Instrumentation and Methods
Abstract We present a Humidity-controlled water-based Fast Imaging Mobility Spectrometer (H-FIMS) capable of rapid measurement of particle hygroscopic growth.
A basic water-based FIMS combines the Fast Imaging Mobility Spectrometer (Kulkarni and Wang, 2006a, b) with laminar flow water condensation methodologies (Hering et al., 2005). The water-based FIMS separates, enlarges and images individual particles to provide complete mobility size distribution measurements over a wide size range with 1-second time resolution.
In the H-FIMS, monodispersed dry particles are first selected by a Differential Mobility Analyzer (DMA). The size-selected particles are humidified, and the resulting size distribution is quickly captured by a water-based FIMS to measure the growth factor and hygroscopicity distributions. By coupling a DMA and a water-based FIMS in series, the H-FIMS system replaces the second DMA of a traditional hygroscopicity tandem DMA (H-TDMA) system with a mobility sizing system that simultaneously measures the sizes of all the humidified particles, greatly increasing the measurement speed.
The performance of H-FIMS was evaluated through laboratory experiments with hygroscopic salts of known behavior, and further through measurements of ambient aerosols. Results show that H-FIMS is able to reproduce, within a few percent, the literature values for the deliquescence and hygroscopic growth of sodium chloride and ammonium sulfate. Ambient data indicate that H-FIMS can measure the hygroscopic growth of six standard dry particle sizes ranging from 35 to 265nm within two minutes, which is an order of magnitude faster than traditional H-TDMA systems.