TY - JOUR

T1 - Nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) for investigating hygroscopic properties of sub-10nm aerosol nanoparticles

AU - Lei, Ting

AU - Ma, Nan

AU - Hong, Juan

AU - Tuch, Thomas

AU - Wang, Xin

AU - Wang, Zhibin

AU - Pöhlker, Mira

AU - Ge, Maofa

AU - Wang, Weigang

AU - Mikhailov, Eugene

AU - Hoffmann, Thorsten

AU - Pöschl, Ulrich

AU - Su, Hang

AU - Wiedensohler, Alfred

AU - Cheng, Yafang

N1 - Funding Information: Acknowledgements. This study was supported by the Max Planck Society (MPG) and Leibniz Society. Ting Lei acknowledges support from the China Scholarship Council (CSC). Yafang Cheng would like to acknowledge the Minerva Program of MPG. Publisher Copyright: © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/10/20

Y1 - 2020/10/20

N2 - Interactions between water and nanoparticles are relevant for atmospheric multiphase processes, physical chemistry, and materials science. Current knowledge of the hygroscopic and related physicochemical properties of nanoparticles, however, is restricted by the limitations of the available measurement techniques. Here, we present the design and performance of a nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) apparatus that enables high accuracy and precision in hygroscopic growth measurements of aerosol nanoparticles with diameters less than 10 nm. Detailed methods of calibration and validation are provided. Besides maintaining accurate and stable sheath and aerosol flow rates (1 %), high accuracy of the differential mobility analyzer (DMA) voltage (0:1 %) in the range of 0-50V is crucial for achieving accurate sizing and small sizing offsets between the two DMAs (1:4 %). To maintain a stable relative humidity (RH), the humidification system and the second DMA are placed in a well-insulated and air conditioner housing (0:1 K). We also tested and discussed different ways of preventing predeliquescence in the second DMA. Our measurement results for ammonium sulfate nanoparticles are in good agreement with Biskos et al. (2006b), with no significant size effect on the deliquescence and efflorescence relative humidity (DRH and ERH, respectively) at diameters down to 6 nm. For sodium sulfate nanoparticles, however, we find a pronounced size dependence of DRH and ERH between 20 and 6 nm nanoparticles.

AB - Interactions between water and nanoparticles are relevant for atmospheric multiphase processes, physical chemistry, and materials science. Current knowledge of the hygroscopic and related physicochemical properties of nanoparticles, however, is restricted by the limitations of the available measurement techniques. Here, we present the design and performance of a nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) apparatus that enables high accuracy and precision in hygroscopic growth measurements of aerosol nanoparticles with diameters less than 10 nm. Detailed methods of calibration and validation are provided. Besides maintaining accurate and stable sheath and aerosol flow rates (1 %), high accuracy of the differential mobility analyzer (DMA) voltage (0:1 %) in the range of 0-50V is crucial for achieving accurate sizing and small sizing offsets between the two DMAs (1:4 %). To maintain a stable relative humidity (RH), the humidification system and the second DMA are placed in a well-insulated and air conditioner housing (0:1 K). We also tested and discussed different ways of preventing predeliquescence in the second DMA. Our measurement results for ammonium sulfate nanoparticles are in good agreement with Biskos et al. (2006b), with no significant size effect on the deliquescence and efflorescence relative humidity (DRH and ERH, respectively) at diameters down to 6 nm. For sodium sulfate nanoparticles, however, we find a pronounced size dependence of DRH and ERH between 20 and 6 nm nanoparticles.

KW - анализатор гигроскопических свойств аэрозолей 10 нм аэрозолей

UR - http://www.scopus.com/inward/record.url?scp=85094621035&partnerID=8YFLogxK

U2 - 10.5194/amt-13-5551-2020

DO - 10.5194/amt-13-5551-2020

M3 - статья

AN - SCOPUS:85094621035

VL - 13

SP - 5551

EP - 5567

JO - Atmospheric Measurement Techniques

JF - Atmospheric Measurement Techniques

SN - 1867-1381

IS - 10

ER -