Fluorescence Aerosol Flow Tube Spectroscopy to Detect Liquid-Liquid Phase Separation

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

18 Scopus Citations
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Author(s)

  • Paul E. Ohno
  • Jianhuai Ye
  • Junfeng Wang
  • Allan K. Bertram
  • Scot T. Martin

Detail(s)

Original languageEnglish
Pages (from-to)1223-1232
Journal / PublicationACS Earth and Space Chemistry
Volume5
Issue number5
Online published6 May 2021
Publication statusPublished - 20 May 2021
Externally publishedYes

Abstract

The phase behavior of atmospheric aerosol particles influences processes like gas-particle partitioning, solar light scattering, and cloud formation, ultimately affecting atmospheric air quality and climate. An important aspect of this phase behavior is whether an individual particle exists in a single homogeneous phase or undergoes liquid-liquid phase separation (LLPS). Herein, fluorescence aerosol flow tube (F-AFT) spectroscopy is developed to characterize LLPS in aerosolized submicron particles of 100-200 nm. A solvatochromic fluorescent probe molecule is incorporated into the particles. The link between its fluorescence emission and the local particle-phase chemical environment is used to determine the separation relative humidity (SRH) at which LLPS occurs. The LLPS behaviors of mixed organic/inorganic particles composed of polyethylene glycol (PEG), ammonium sulfate (AS), and sodium chloride (NaCl) are characterized. PEG/AS particles undergo LLPS at SRH values that vary with PEG composition. By comparison, PEG/NaCl particles continue as a single homogeneous phase to the RH of NaCl crystallization. The SRH values for the submicron particles are lower by >5% RH than those reported in the literature for supermicron particles deposited to substrate surfaces. Possible reasons for the differences are discussed, including kinetic and thermodynamic effects of system size and foreign substrate as well as observation time in the experimental apparatus. © 2021 American Chemical Society.

Research Area(s)

  • aerosol particles, fluorescence, Liquid-liquid phase separation, Nile Red, spectroscopy

Citation Format(s)

Fluorescence Aerosol Flow Tube Spectroscopy to Detect Liquid-Liquid Phase Separation. / Ohno, Paul E.; Qin, Yiming; Ye, Jianhuai et al.
In: ACS Earth and Space Chemistry, Vol. 5, No. 5, 20.05.2021, p. 1223-1232.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review