Probing the bulk viscosity of particles using aerosol optical tweezers.

Rory Power*, David L. Bones, Jonathan P. Reid

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

3 Citations (Scopus)

Abstract

Holographic aerosol optical tweezers can be used to trap arrays of aerosol particles allowing detailed studies of particle properties and processes at the single particle level. Recent observations have suggested that secondary organic aerosol may exist as ultra-viscous liquids or glassy states at low relative humidity, potentially a significant factor in influencing their role in the atmosphere and their activation to form cloud droplets. A decrease in relative humidity surrounding a particle leads to an increased concentration of solute in the droplet as the droplet returns to equilibrium and, thus, an increase in the bulk viscosity. We demonstrate that the timescales for condensation and evaporation processes correlate with particle viscosity, showing significant inhibition in mass transfer kinetics using ternary sucrose/sodium chloride/water droplets as a proxy to atmospheric multi-component aerosol. We go on to study the fundamental process of aerosol coagulation in aerosol particle arrays, observing the relaxation of non-spherical composite particles formed on coalescence. We demonstrate the use of bright-field imaging and elastic light scattering to make measurements of the timescale for the process of binary coalescence contrasting the rheological properties of aqueous sucrose and sodium chloride aerosol over a range of relative humidities.

Original languageEnglish
Title of host publicationOPTICAL TRAPPING AND OPTICAL MICROMANIPULATION IX
EditorsK Dholakia, GC Spalding
Place of PublicationBELLINGHAM
PublisherSociety of Photo-Optical Instrumentation Engineers (SPIE)
Number of pages10
ISBN (Print)978-0-8194-9175-6
DOIs
Publication statusPublished - 2012
EventOptical Trapping and Optical Micromanipulation IX - San Diego Convention Center, San Diego, CA, United States
Duration: 12 Aug 201216 Aug 2012

Publication series

NameProceedings of SPIE
PublisherSPIE-INT SOC OPTICAL ENGINEERING
Volume8458
ISSN (Print)0277-786X

Conference

ConferenceOptical Trapping and Optical Micromanipulation IX
CountryUnited States
CitySan Diego, CA
Period12/08/1216/08/12

Keywords

  • optical trapping and manipulation
  • glassy aerosol and aerosol coagulation

Projects

Cite this

Power, R., Bones, D. L., & Reid, J. P. (2012). Probing the bulk viscosity of particles using aerosol optical tweezers. In K. Dholakia, & GC. Spalding (Eds.), OPTICAL TRAPPING AND OPTICAL MICROMANIPULATION IX (Proceedings of SPIE; Vol. 8458). Society of Photo-Optical Instrumentation Engineers (SPIE). https://doi.org/10.1117/12.931655