Changing shapes and implied viscosities of suspended submicron particles
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 part...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/15/7819/2015/acp-15-7819-2015.pdf |
| _version_ | 1811239965805248512 |
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| author | 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 |
| author_facet | 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 |
| author_sort | Y. Zhang |
| collection | DOAJ |
| description | 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<sup>(8.7±2.0)</sup> to
10<sup>(7.0±2.0)</sup> 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. |
| first_indexed | 2024-04-12T13:12:00Z |
| format | Article |
| id | doaj.art-9d404471d52f4319beedb11e28f230fe |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-12T13:12:00Z |
| publishDate | 2015-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-9d404471d52f4319beedb11e28f230fe2022-12-22T03:31:51ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242015-07-0115147819782910.5194/acp-15-7819-2015Changing shapes and implied viscosities of suspended submicron particlesY. Zhang0M. S. Sanchez1C. Douet2Y. Wang3A. P. Bateman4Z. Gong5M. Kuwata6L. Renbaum-Wolff7B. B. Sato8P. F. Liu9A. K. Bertram10F. M. Geiger11S. T. Martin12School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USASchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USASchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USASchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USASchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USASchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USASchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USADepartment of Chemistry, University of British Columbia, Vancouver, British Columbia, CanadaSchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USASchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USADepartment of Chemistry, University of British Columbia, Vancouver, British Columbia, CanadaDepartment of Chemistry, Northwestern University, Evanston, Illinois, USASchool of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USAThe 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<sup>(8.7±2.0)</sup> to 10<sup>(7.0±2.0)</sup> 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.http://www.atmos-chem-phys.net/15/7819/2015/acp-15-7819-2015.pdf |
| spellingShingle | 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 Changing shapes and implied viscosities of suspended submicron particles Atmospheric Chemistry and Physics |
| title | Changing shapes and implied viscosities of suspended submicron particles |
| title_full | Changing shapes and implied viscosities of suspended submicron particles |
| title_fullStr | Changing shapes and implied viscosities of suspended submicron particles |
| title_full_unstemmed | Changing shapes and implied viscosities of suspended submicron particles |
| title_short | Changing shapes and implied viscosities of suspended submicron particles |
| title_sort | changing shapes and implied viscosities of suspended submicron particles |
| url | http://www.atmos-chem-phys.net/15/7819/2015/acp-15-7819-2015.pdf |
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