Direct imaging of changes in aerosol particle viscosity upon hydration and chemical aging
File(s)
Published version
Supporting information
Author(s)
Type
Journal Article
Abstract
Organic aerosol particles (OA) play major roles in atmospheric chemistry, climate, and public health. Aerosol particle viscosity is highly important since it can determine the ability of chemical species such as oxidants, organics or water to diffuse into the particle bulk. Recent measurements indicate that OA may be present in highly viscous states, however, diffusion rates of small molecules such as water are not limited by these high viscosities. Direct observational evidence of kinetic barriers caused by high viscosity and low diffusivity in aerosol particles were not available until recently; and techniques that are able to dynamically quantify and track viscosity changes during atmospherically relevant processes are still unavailable for atmospheric aerosols. Here we report quantitative, real-time, online observations of microscopic viscosity changes in aerosol particles of atmospherically relevant composition, using fluorescence lifetime imaging (FLIM) of viscosity. We show that microviscosity in ozonated oleic acid droplets and secondary organic aerosol (SOA) particles formed by ozonolysis of myrcene increases substantially with decreasing humidity and atmospheric oxidative aging processes. Furthermore, we found unexpected heterogeneities of microviscosity inside individual aerosol particles. The results of this study enhance our understanding of organic aerosol processes on microscopic scales and may have important implications for the modeling of atmospheric aerosol growth, composition and interactions with trace gases and clouds.
Date Issued
2016-02-01
Date Acceptance
2015-11-07
Citation
Chemical Science, 2016, 7 (2), pp.1357-1367
ISSN
2041-6539
Publisher
Royal Society of Chemistry
Start Page
1357
End Page
1367
Journal / Book Title
Chemical Science
Volume
7
Issue
2
Copyright Statement
© 2015 The Authors. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/)
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000368835300064&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
EP/I003983/1
Subjects
Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Chemistry
SECONDARY ORGANIC AEROSOL
OLEIC-ACID
LIVE CELLS
ATMOSPHERIC AEROSOLS
PHASE-SEPARATION
WATER DIFFUSION
ICE NUCLEATION
OZONOLYSIS
MODEL
STATE
03 Chemical Sciences
Publication Status
Published
Date Publish Online
2015-11-12