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Nature of Temperature-Induced Phase Transitions in Secondary Organic Aerosol Particles

Jensen, Louise N. ; Kristensen, Kasper ; Iversen, Emil M. ; Canagaratna, Manjula R. ; Roldin, Pontus LU and Bilde, Merete (2025) In Environmental Science and Technology 59(45). p.24359-24367
Abstract

This study investigates how changes in temperature affect the secondary organic aerosol (SOA) phase state. SOA was formed by α-pinene ozonolysis in an atmospheric simulation chamber at temperatures (T0) in the range of 257–283 K at RH0< 20%. After more than 14 h of SOA aging, one or more heating and cooling ramps were performed. Upon heating, we observe that the onset of evaporative SOA shrinkage is delayed by up to ∼20 K relative to T0. Our observations are supported by aerosol dynamics and kinetic multilayer model simulations, relating observed changes to an effectively reversible temperature- and SOA-composition-dependent phase transition from solid glassy to semisolid. We demonstrate that the SOA... (More)

This study investigates how changes in temperature affect the secondary organic aerosol (SOA) phase state. SOA was formed by α-pinene ozonolysis in an atmospheric simulation chamber at temperatures (T0) in the range of 257–283 K at RH0< 20%. After more than 14 h of SOA aging, one or more heating and cooling ramps were performed. Upon heating, we observe that the onset of evaporative SOA shrinkage is delayed by up to ∼20 K relative to T0. Our observations are supported by aerosol dynamics and kinetic multilayer model simulations, relating observed changes to an effectively reversible temperature- and SOA-composition-dependent phase transition from solid glassy to semisolid. We demonstrate that the SOA content of highly oxygenated organic molecules (HOMs) increases with T0and at lower α-pinene concentrations. Higher HOM SOA content results in more viscous SOA with a higher glass transition temperature (Tg). The model was used to quantify how Tgvaries with T0and the amount of α-pinene being oxidized. Because the SOA phase state is influenced by the conditions under which it forms, and affects SOA lifetime, reactivity, water uptake, and potentially ice nucleating properties, the results presented herein may have wide implications for the design of future SOA experiments, air quality, and climate.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
alpha-pinene, phase transition, secondary organic aerosol, viscosity
in
Environmental Science and Technology
volume
59
issue
45
pages
9 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:105022126324
  • pmid:41202158
ISSN
0013-936X
DOI
10.1021/acs.est.5c08582
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Authors. Published by American Chemical Society
id
c53f6562-f522-4422-adfa-2a5236d190da
date added to LUP
2026-01-22 10:31:07
date last changed
2026-01-22 10:31:26
@article{c53f6562-f522-4422-adfa-2a5236d190da,
  abstract     = {{<p>This study investigates how changes in temperature affect the secondary organic aerosol (SOA) phase state. SOA was formed by α-pinene ozonolysis in an atmospheric simulation chamber at temperatures (T<sub>0</sub>) in the range of 257–283 K at RH<sub>0</sub>&lt; 20%. After more than 14 h of SOA aging, one or more heating and cooling ramps were performed. Upon heating, we observe that the onset of evaporative SOA shrinkage is delayed by up to ∼20 K relative to T<sub>0</sub>. Our observations are supported by aerosol dynamics and kinetic multilayer model simulations, relating observed changes to an effectively reversible temperature- and SOA-composition-dependent phase transition from solid glassy to semisolid. We demonstrate that the SOA content of highly oxygenated organic molecules (HOMs) increases with T<sub>0</sub>and at lower α-pinene concentrations. Higher HOM SOA content results in more viscous SOA with a higher glass transition temperature (T<sub>g</sub>). The model was used to quantify how T<sub>g</sub>varies with T<sub>0</sub>and the amount of α-pinene being oxidized. Because the SOA phase state is influenced by the conditions under which it forms, and affects SOA lifetime, reactivity, water uptake, and potentially ice nucleating properties, the results presented herein may have wide implications for the design of future SOA experiments, air quality, and climate.</p>}},
  author       = {{Jensen, Louise N. and Kristensen, Kasper and Iversen, Emil M. and Canagaratna, Manjula R. and Roldin, Pontus and Bilde, Merete}},
  issn         = {{0013-936X}},
  keywords     = {{alpha-pinene; phase transition; secondary organic aerosol; viscosity}},
  language     = {{eng}},
  month        = {{11}},
  number       = {{45}},
  pages        = {{24359--24367}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Environmental Science and Technology}},
  title        = {{Nature of Temperature-Induced Phase Transitions in Secondary Organic Aerosol Particles}},
  url          = {{http://dx.doi.org/10.1021/acs.est.5c08582}},
  doi          = {{10.1021/acs.est.5c08582}},
  volume       = {{59}},
  year         = {{2025}},
}