Preprints
https://doi.org/10.5194/amt-2022-151
https://doi.org/10.5194/amt-2022-151
 
16 May 2022
16 May 2022
Status: this preprint is currently under review for the journal AMT.

A New Hot-Stage Microscopy Technique for Measuring Temperature-Dependent Viscosities of Aerosol Particles and its Application to Farnesene Secondary Organic Aerosol

Kristian J. Kiland1, Kevin L. Marroquin1, Natalie R. Smith2, Shaun Xu1, Sergey A. Nizkorodov2, and Allan K. Bertram1 Kristian J. Kiland et al.
  • 1Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
  • 2Department of Chemistry, University of California Irvine, Irvine, California 92697, USA

Abstract. The viscosity of secondary organic aerosols (SOA) is needed to predict their influence on air quality, climate, and atmospheric chemistry. Many techniques have been developed to measure the viscosity of micrometer-sized materials at room temperature, however, few techniques are able to measure viscosity as a function of temperature for these small sample sizes. SOA in the troposphere experience a wide range of temperatures, so measurement of viscosity as a function of temperature is needed. To address this need, a new method was developed based on hot-stage microscopy combined with fluid dynamics simulations. To validate our technique, the viscosity of 1,3,5-tris(1-naphthyl)benzene was measured and compared with values reported in the literature. Good agreement was found between our measurements and literature data. As an application to SOA, the viscosity as a function of temperature for lab-generated farnesene SOA was measured, giving values ranging from 3.4 × 106 Pa s at 51 °C to 2.6 × 104 Pa s at 67 °C. These values were significantly higher (1–2 orders of magnitude) than values predicted using a parameterization from DeRieux et al. (2018), the chemical composition of the SOA measured with a high-resolution mass spectrometer, and assuming a fragility of 10 (as done previously). These results illustrate that our new experimental approach provides important data for testing methods used for predicting the viscosities of SOA in the atmosphere.

Kristian J. Kiland et al.

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-151', Anonymous Referee #1, 24 May 2022 reply

Kristian J. Kiland et al.

Kristian J. Kiland et al.

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Short summary
Information on the viscosity of secondary organic aerosols is needed when making air quality, climate, and atmospheric chemistry predictions. Viscosity depends on temperature, so we developed a new method for measuring the temperature-dependent viscosity of small samples. As an application of the method, we measured the viscosity of farnesene secondary organic aerosol at different temperatures.