Modeling the thermodynamics and kinetics of sulfuric acid-dimethylamine-water nanoparticle growth in the CLOUD chamber

Autor(en)

L. Ahlm, T. Yli-Juuti, S. Schobesberger, A. P. Praplan, J. Kim, O. -P. Tikkanen, M. J. Lawler, J. N. Smith, J. Tröstl, J. C. Acosta Navarro, U. Baltensperger, F. Bianchi, N. M. Donahue, J. Duplissy, A. Franchin, T. Jokinen, H. Keskinen, J. Kirkby, A. Kürten, A. Laaksonen, K. Lehtipalo, T. Petäjä, F. Riccobono, M. P. Rissanen, L. Rondo, S. Schallhart, M. Simon, Paul Winkler, D. R. Worsnop, A. Virtanen, I. Riipinen

Abstrakt

Dimethylamine (DMA) has a stabilizing effect on sulfuric acid (SA) clusters, and the SA and DMA molecules and clusters likely play important roles in both aerosol particle formation and growth in the atmosphere. We use the monodisperse particle growth model for acid-base chemistry in nanoparticle growth (MABNAG) together with direct and indirect observations from the CLOUD4 and CLOUD7 experiments in the cosmics leaving outdoor droplets (CLOUD) chamber at CERN to investigate the size and composition evolution of freshly formed particles consisting of SA, DMA, and water as they grow to 20 nm in dry diameter. Hygroscopic growth factors are measured using a nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA), which combined with simulations of particle water uptake using the thermodynamic extended-aerosol inorganics model (E-AIM) constrain the chemical composition. MABNAG predicts a particle-phase ratio between DMA and SA molecules of 1.1–1.3 for a 2 nm particle and DMA gas-phase mixing ratios between 3.5 and 80 pptv. These ratios agree well with observations by an atmospheric-pressure interface time-of-flight (APi-TOF) mass spectrometer. Simulations with MABNAG, direct observations of the composition of clusters <2 nm, and indirect observations of the particle composition indicate that the acidity of the nucleated particles decreases as they grow from ∼1 to 20 nm. However, MABNAG predicts less acidic particles than suggested by the indirect estimates at 10 nm diameter using the nano-HTDMA measurements, and less acidic particles than observed by a thermal desorption chemical ionization mass spectrometer (TDCIMS) at 10–30 nm. Possible explanations for these discrepancies are discussed.

Organisation(en)

Aerosolphysik und Umweltphysik

Externe Organisation(en)

Stockholm University, University of Eastern Finland, University of Helsinki, University of Washington, University of California, Irvine, Paul Scherrer Institute, Eidgenössische Technische Hochschule Zürich, Carnegie Mellon University, European Organization for Nuclear Research (CERN), Johann Wolfgang Goethe-Universität Frankfurt am Main, Universität Wien, Aerodyne Res Inc

Journal

Aerosol Science and Technology

Band

50

Seiten

1017-1032

Anzahl der Seiten

16

ISSN

0278-6826

DOI

https://doi.org/10.1080/02786826.2016.1223268

Publikationsdatum

2016

Peer-reviewed

Ja

ÖFOS 2012

103037 Umweltphysik, 103039 Aerosolphysik

Schlagwörter

ASJC Scopus Sachgebiete

Pollution, Allgemeine Materialwissenschaften, Environmental Chemistry

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/67d7fac8-b560-4b58-9815-4850a054eadc