edu.ucar.opensky::articles:18289 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T02:56:42.629797 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7183830 Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments 2016-01-18T00:00:00Z publication https://n2t.org/ark:/85065/d7183830 https://doi.org/10.5194/acp-16-293-2016 Kim, J. author Ahlm, L. author Yli-Juuti, T. author Lawler, Michael J. author Keskinen, H. author Trostl, J. author Schobesberger, S. author Duplissy, J. author Amorim, A. author Bianchi, F. author Donahue, N. author Flagan, R. author Hakala, J. author Heinritzi, M. author Jokinen, T. author Kurten, A. author Laaksonen, A. author Lehtipalo, K. author Miettinen, P. author Petaja, T. author Rissanen, M. author Rondo, L. author Sengupta, K. author SImon, M. author Tome, A. author Williamson, C. author Wimmer, D. author WInkler, P. author Ehrhart, S. author Ye, P. author Kirkby, J. author Curtius, J. author Baltensperger, U. author Kulmala, M. author Lehtinen, K. author Smith, James N. author Riipinen, I. author Virtanen, A. author UCAR/NCAR - Library publisher Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study, we focus on a challenging size range, i.e., particles that have grown to diameters of 10 and 15 nm following nucleation, and measure their water uptake. Water uptake is useful information for indirectly obtaining chemical composition of aerosol particles. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at subsaturated conditions (ca. 90 % relative humidity at 293 K) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) campaign performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from α-pinene oxidation. The hygroscopicity parameter κ decreased with increasing particle size, indicating decreasing acidity of particles. No clear effect of the sulfuric acid concentration on the hygroscopicity of 10 nm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15 nm particles sharply decreased with decreasing sulfuric acid concentrations. In particular, when the concentration of sulfuric acid was 5.1 × 106 molecules cm−3 in the gas phase, and the dimethylamine mixing ratio was 11.8 ppt, the measured κ of 15 nm particles was 0.31 ± 0.01: close to the value reported for dimethylaminium sulfate (DMAS) (κDMAS ∼ 0.28). Furthermore, the difference in κ between sulfuric acid and sulfuric acid-imethylamine experiments increased with increasing particle size. The κ values of particles in the presence of sulfuric acid and organics were much smaller than those of particles in the presence of sulfuric acid and dimethylamine. This suggests that the organics produced from α-pinene ozonolysis play a significant role in particle growth even at 10 nm sizes. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License None eng geoscientificInformation