Characterization of a high-resolution supercritical differential mobility analyzer at reduced flow rates

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Cai , R , Attoui , M , Jiang , J , Korhonen , F , Hao , J , Petäjä , T & Kangasluoma , J 2018 , ' Characterization of a high-resolution supercritical differential mobility analyzer at reduced flow rates ' , Aerosol Science and Technology , vol. 52 , no. 11 , pp. 1332-1343 . https://doi.org/10.1080/02786826.2018.1520964

Title: Characterization of a high-resolution supercritical differential mobility analyzer at reduced flow rates
Author: Cai, Runlong; Attoui, Michel; Jiang, Jingkun; Korhonen, Frans; Hao, Jiming; Petäjä, Tuukka; Kangasluoma, Juha
Contributor: University of Helsinki, INAR Physics
University of Helsinki, Institute for Atmospheric and Earth System Research (INAR)
University of Helsinki, Institute for Atmospheric and Earth System Research (INAR)
University of Helsinki, Institute for Atmospheric and Earth System Research (INAR)
University of Helsinki, INAR Physics
Date: 2018-11-02
Language: eng
Number of pages: 12
Belongs to series: Aerosol Science and Technology
ISSN: 0278-6826
URI: http://hdl.handle.net/10138/306285
Abstract: Classifying sub-3 nm particles effectively with relatively high penetration efficiencies and sizing resolutions is important for atmospheric new particle formation studies. A high-resolution supercritical differential mobility analyzer (half-mini DMA) was recently improved to classify aerosols at a sheath flow rate less than 100 L/min. In this study, we characterized the transfer functions, the penetration efficiencies, and the sizing resolution of the new half-mini DMA at the aerosol flow rate of 2.5-10 L/min and the sheath flow rate of 25-250 L/min using tetra-alkyl ammonium ions and tungsten oxide particles. The transfer functions of the new half-mini DMA at an aerosol flow rate lower than 5 L/min and a sheath flow rate lower than 150 L/min agree well with predictions using a theoretical diffusing transfer function. The penetration efficiencies can be approximated using an empirical formula. When classifying 1.48 nm molecular ions at an aerosol-to-sheath flow ratio of 5/50 L/min, the penetration efficiency, the sizing resolution, and the multiplicative broadening factor of the new half-mini DMA are 0.18, 6.8, and 1.11, respectively. Compared to other sub-3 nm DMAs applied in atmospheric measurements (e.g. the mini-cyDMA, the TSI DMA 3086, the TSI nanoDMA 3085, and the Grimm S-DMA), the new half-mini DMA characterized in this study is able to classify particles at higher aerosol and sheath flow rates, leading to a higher sizing resolution at the same aerosol-to-sheath flow ratio. Accordingly, the new half-mini DMA can reduce the uncertainties in atmospheric new particle formation measurement if coupled with an aerosol detector that could work at the corresponding high aerosol flow rate. (c) 2018 American Association for Aerosol Research
Subject: OPPOSED MIGRATION ION
PARTICLE CLASSIFICATION
AEROSOL
DMA
DESIGN
NANOPARTICLES
GENERATION
NUCLEATION
STANDARDS
RANGE
1172 Environmental sciences
114 Physical sciences
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