Tandem configuration of differential mobility and centrifugal particle mass analysers for investigating aerosol hygroscopic properties

• Main Authors: S. S. Vlasenko, H. Su, U. Pöschl, M. O. Andreae, E. F. Mikhailov
• Format: Article
• Language: English
• Published: Copernicus Publications 2017-03-01
• Series: Atmospheric Measurement Techniques
• Online Access: http://www.atmos-meas-tech.net/10/1269/2017/amt-10-1269-2017.pdf
• ISSN: 1867-1381; 1867-8548

A tandem arrangement of Differential Mobility Analyser and Humidified Centrifugal Particle Mass Analyser (DMA-HCPMA) was developed to measure the deliquescence and efflorescence thresholds and the water uptake of submicron particles over the relative humidity (RH) range from 10 to 95 %. The hygroscopic growth curves obtained for ammonium sulfate and sodium chloride test aerosols are consistent with thermodynamic model predictions and literature data. The DMA-HCPMA system was applied to measure the hygroscopic properties of urban aerosol particles, and the kappa mass interaction model (KIM) was used to characterize and parameterize the concentration-dependent water uptake observed in the 50–95 % RH range. For DMA-selected 160 nm dry particles (modal mass of 3.5 fg), we obtained a volume-based hygroscopicity parameter, <i>κ</i>_<i>v</i> ≈  0.2, which is consistent with literature data for freshly emitted urban aerosols.<br><br>Overall, our results show that the DMA-HCPMA system can be used to measure size-resolved mass growth factors of atmospheric aerosol particles upon hydration and dehydration up to 95 % RH. Direct measurements of particle mass avoid the typical complications associated with the commonly used mobility-diameter-based HTDMA technique (mainly due to poorly defined or unknown morphology and density).