Changing shapes and implied viscosities of suspended submicron particles

Y. Zhang, M. S. Sanchez, C. Douet, Y. Wang, A. P. Bateman, Z. Gong, M. Kuwata, L. Renbaum-Wolff, B. B. Sato, P. F. Liu, A. K. Bertram, F. M. Geiger, S. T. Martin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Scopus citations

Abstract

The change in shape of atmospherically relevant organic particles is used to estimate the viscosity of the particle material without the need for removal from aerosol suspension. The dynamic shape factors χ of particles produced by α-pinene ozonolysis in a flow tube reactor, under conditions of particle coagulation, were measured while altering the relative humidity (RH) downstream of the flow tube. As relative humidity was increased, the results showed that χ could change from 1.27 to 1.02, corresponding to a transition from aspherical to nearly spherical shapes. The shape change could occur at elevated RH because the organic material had decreased viscosity and was therefore able to flow to form spherical shapes, as favored by the minimization of surface area. Numerical modeling was used to estimate the particle viscosity associated with this flow. Based on particle diameter and RH exposure time, the viscosity dropped from 10(8.7±2.0) to 10(7.0±2.0) Pa s (two sigma) for an increase in RH from < 5 to 58 % at 293 K. These results imply that the equilibration of the chemical composition of the particle phase with the gas phase can shift from hours at mid-range RH to days at low RH.

Original languageEnglish (US)
Pages (from-to)7819-7829
Number of pages11
JournalAtmospheric Chemistry and Physics
Volume15
Issue number14
DOIs
StatePublished - Jul 16 2015

ASJC Scopus subject areas

  • Atmospheric Science

Fingerprint Dive into the research topics of 'Changing shapes and implied viscosities of suspended submicron particles'. Together they form a unique fingerprint.

Cite this