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Physical states of mixed organic-inorganic aerosols

English title Physical states of mixed organic-inorganic aerosols
Applicant Peter Thomas
Number 146760
Funding scheme Project funding (Div. I-III)
Research institution Institut für Atmosphäre und Klima ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Climatology. Atmospherical Chemistry, Aeronomy
Start/End 01.09.2013 - 31.05.2017
Approved amount 328'484.00
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Keywords (6)

RADIATIVE FORCING; MIE RESONANCE SPECTROSCOPY; EFFLORESCENCE/DELIQUESCENCE; THERMODYNAMICS; ORGANIC AEROSOLS; MISCIBILITY GAPS

Lay Summary (German)

Lead
Aerosole spielen eine wichtige Rolle bei der Wolkenbildung und sie beeinflussen die Strahlungsbilanz der Atmosphäre, indem sie Sonnenlicht absorbieren und streuen. Viele dieser Prozesse hängen stark von der Zusammensetzung der Aerosolpartikel und ihrem Phasenzustand ab. Die Auswirkungen der Aerosolzusammensetzung und des Phasenzustands auf die Wolkenbildung und Lichtstreuung ist noch nicht genügend verstanden und führt zu grossen Unsicherheiten in regionalen und globalen Klimamodellen.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Aerosolpartikel können als kristalline Feststoffe, Gläser, flüssige Partikel, oder Mischungen dieser Phasen vorliegen. Zurzeit ist jedoch nicht klar, wie die chemische Zusammensetzung der Aerosole den Phasenzustand der Partikel beeinflusst und welchen Einfluss der Phasenzustand der Partikel auf die Wolkenbildung und Lichtstreuung hat. Das Ziel des Forschungsprojekts ist es, das Verständnis dieser Prozesse zu verbessern. Dazu sollen Aerosolpartikel bestehend aus typischen Aerosolkomponenten in Abhängigkeit der relativen Feuchte untersucht werden. Für diese Untersuchungen stehen zwei verschiedene Instrumente zur Verfügung. Wir benutzen ein Lichtmikroskop um Phasenübergange von Aerosolpartikeln, die auf ein hydrophob beschichtetes Substrat abgeschieden worden sind, optisch zu beobachten während wir die relative Feuchte in der Zelle variieren. In unserer elektrodynamischen Falle können wir Aerosolpartikel in der Schwebe halten und die Wasseraufnahme und –abgabe beobachten während wir die relative Feuchte variieren. Im vorliegenden Projekt werden wir gezielt Aerosolpartikel hinsichtlich ihrer Phasen und Morphologie mit diesen beiden Geräten untersuchen.

 

Wissenschaftlicher Kontext des Forschungsprojekts

Diese Studie wird eine bessere Repräsentation von Aerosolprozessen in Klimamodellen erlauben.

Direct link to Lay Summary Last update: 27.08.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Time evolution of steep diffusion fronts in highly viscous aerosol particles measured with Mie resonance spectroscopy
Bastelberger S., Krieger U. K., Luo B. P., Peter Th. (2018), Time evolution of steep diffusion fronts in highly viscous aerosol particles measured with Mie resonance spectroscopy, in The Journal of Chemical Physics, 149(24), 244506-244506.
Shortwave radiative impact of liquid–liquid phase separation in brown carbon aerosols
Fard Mehrnoush M., Krieger Ulrich K., Peter Thomas (2018), Shortwave radiative impact of liquid–liquid phase separation in brown carbon aerosols, in Atmospheric Chemistry and Physics, 18(18), 13511-13530.
Kinetic Limitation to Inorganic Ion Diffusivity and to Coalescence of Inorganic Inclusions in Viscous Liquid–Liquid Phase-Separated Particles
Fard Mehrnoush M., Krieger Ulrich K., Peter Thomas (2017), Kinetic Limitation to Inorganic Ion Diffusivity and to Coalescence of Inorganic Inclusions in Viscous Liquid–Liquid Phase-Separated Particles, in The Journal of Physical Chemistry A, 121(48), 9284-9296.
Diffusivity measurements of volatile organics in levitated viscous aerosol particles
Bastelberger Sandra, Krieger Ulrich K., Peter Thomas, Luo Beiping (2017), Diffusivity measurements of volatile organics in levitated viscous aerosol particles, in Atmospheric Chemistry and Physics, 17, 8453-8471.
Revising the hygroscopicity of inorganic sea salt particles
Zieger Paul, Bastelberger Sandra, Mousavi-Fard Mehrnoush, Krieger Ulrich K., et al. (2017), Revising the hygroscopicity of inorganic sea salt particles, in Nature Communications, 8, 15883.

Collaboration

Group / person Country
Types of collaboration
PSI, Prof. U. Baltensperger Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
ETHZ, IAC, Prof. U. Lohmann Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Weizmann Institute, Prof. Y. Rudich Israel (Asia)
- in-depth/constructive exchanges on approaches, methods or results
Univ Bristol, Prof. J. P. Reid Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
European Geosciences Union General Assembly 2017 Poster Diffusivity Measurements of Volatile Organics in Levitated Viscous Aerosol Particles 23.04.2017 Wien, Austria Krieger Ulrich; Peter Thomas; Bastelberger Sandra Tuyêt-Lan;
A Molecular Understanding of Atmospheric Aerosols Talk given at a conference Effect of Liquid-Liquid Phase Separation on the Absorption Cross Section of Aerosol Particles Containing Brown or Black Carbon 28.08.2016 Santa Cruz, United States of America Krieger Ulrich; Mousavi-Fard Mehrnoush;
European Geosciences Union General Assembly 2016 Poster Tracking Water Diffusion Fronts in a Highly Viscous Aerosol Particle 17.04.2016 Wien, Austria Bastelberger Sandra Tuyêt-Lan; Peter Thomas; Krieger Ulrich;
European Geosciences Union General Assembly 2016 Poster Morphology and Optical Properties of Mixed Aerosol Particles 17.04.2016 Wien, Austria Mousavi-Fard Mehrnoush; Peter Thomas; Krieger Ulrich;
INTERNATIONAL AEROSOL MODELING ALGORITHMS (IAMA) 2015 Dynamic Models Branching Out to Explain an Evolving Atmosphere Talk given at a conference Redistribution of Black and Brown Carbon in Aerosol Particles Undergoing Liquid-Liquid Phase Separation 09.12.2015 Davis, United States of America Krieger Ulrich;
European Aerosol Conference Poster Morphology and optical properties of mixed aerosol particles 06.09.2015 Milano, Italy Mousavi-Fard Mehrnoush;
15th Electromagnetic and Light Scattering Conference Poster Mie resonance shifts as experimental mean to track water diffusion fronts inside of a highly viscous aerosol particle 21.06.2015 Leipzig, Germany Bastelberger Sandra Tuyêt-Lan;
European Geosciences Union General Assembly 2015 Poster Morphology and Optical Properties of Mixed Aerosol Particles 12.04.2015 Wien, Austria Krieger Ulrich; Mousavi-Fard Mehrnoush; Peter Thomas;
Towards a molecular-level understanding of atmospheric aerosols Talk given at a conference Measuring and modeling concentration gradients in single semi-solid organic aerosol particles 31.08.2014 Ascona, Switzerland Bastelberger Sandra Tuyêt-Lan; Krieger Ulrich;
Towards a molecular-level understanding of atmospheric aerosols Poster Morphology and Optical Properties of Mixed Aerosol Particles 31.08.2014 Ascona, Switzerland Mousavi-Fard Mehrnoush;
European Geosciences Union General Assembly 2014 Poster Inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy 27.04.2014 Wien, Austria Bastelberger Sandra Tuyêt-Lan; Krieger Ulrich;
AGU Fall meeting Talk given at a conference Radial inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy 09.12.2013 San Francisco, United States of America Krieger Ulrich;


Self-organised

Title Date Place

Associated projects

Number Title Start Funding scheme
143996 9-months extension request for SNF Project No. 200020-125151: "Physical states of mixed organic-inorganic aerosols" 01.10.2012 Project funding (Div. I-III)
103651 Physical states of mixed organic / inorganic aerosols 01.11.2004 Project funding (Div. I-III)
156251 Ice freezing on mineral dust samples 01.03.2015 Project funding (Div. I-III)
143996 9-months extension request for SNF Project No. 200020-125151: "Physical states of mixed organic-inorganic aerosols" 01.10.2012 Project funding (Div. I-III)
163074 Feedbacks between atmospheric aerosol microphysics and photochemical aging 01.01.2016 Project funding (Div. I-III)
189939 Infectivity of influenza viruses in expiratory aerosols under ambient temperatures and humidities (IVEA) 01.06.2020 Sinergia
108032 The effects of organic compounds on the hygroscopic properties of inorganic aerosols 01.07.2005 Project funding (Div. I-III)
63328 Einfluss von Organika auf atmosphärische wässrige Aerosole 01.04.2002 Project funding (Div. I-III)

Abstract

Aerosols are an integral part of the atmospheric hydrological cycle and radiation budget, with many possible feedback mechanisms that are far from being fully understood. To reduce the uncertainties connected with aerosol forcings, a better physical understanding of the aerosols, their mixing states and properties, and a better representation in regional and global models is needed. Recently, experiments and modeling studies have shown that deliquesced aerosols can be present not only as one-phase systems containing organics, inorganic salts and water, but often as two-phase systems consisting of a predominantly organic and a predominantly inorganic aqueous phase. Also, there is growing evidence that aerosol particles containing a large fraction of organic molecules with medium to high molecular weight tend to become highly viscous or even glassy at low humidities and/or low temperatures. An important consequence of phase separation or glass formation is that the aerosol particles are no longer homogeneous, but may exhibit strong internal concentration gradients. Within SNF projects 200020-103651 and 200020-125151 (Physical states of mixed organic / inorganic aerosols) we were able to demonstrate the occurrence of liquid-liquid phase separation (LLPS) for a wide range of organics as function of O:C ratios and functional group compositions. However, in these studies we always used fully neutralized aqueous ammonium sulfate as inorganic component. In contrast, in the atmosphere the aerosol is often not fully neutralized or contains in addition ammonium nitrate. Hardly any data on the physical state of such acidic or nitrate-containing organic/inorganic mixed particles are available. It has been shown that forcing a liquid one-phase aerosol bears the potential for vastly incorrect gas/particle partitioning predictions with repercussions for the aerosol radiative properties. Moreover, the morphologies of phase separated particles and the diffusion impedance in highly viscous or glassy particles are open issues. Conversely, regional and global models are approaching a stage enabling incorporation of aerosol phase state information. In this continuation project for two PhD students we intend to investigate the phases and morphologies of aerosol particles depending on atmospherically relevant particle composi-tions, relative humidity and temperature. In PhD work I, we intend to investigate the phases and morphologies of aerosol particles in relation to the O:C ratio of the organic fraction for different atmospherically relevant inorganic particle compositions. Inorganic aerosol compositions will comprise partially neutralized sulfates and mixtures of ammonium sulfate and nitrate. Most experiments will be carried out on single particles deposited on a hydrophobically coated substrate observed with light and Raman microscopy. In PhD work II, we propose to investigate the internal heterogeneity of aerosol particles. Mie resonance spectra of single particles levitated in our electrodynamic balance will be used to characterize the phase volumes and concentration gradients quantitatively and to validate the liquid diffusion model that we developed recently. The diffusion model can be applied to aerosol particles of atmospheric sizes to study the impact of water uptake impedance on e.g. lifetime of particles and the direct effect of aerosol on radiation.Both PhD students will work closely together, partially investigate the same model systems with complementary methods and merge their results to obtain a comprehensive understanding of the morphology of aerosol particles. They will have the opportunity to also become involved in other ongoing projects of our group and collaborations with other ETH groups, with the aim to implement their results into regional and global models.
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