Campbell, JM orcid.org/0000-0002-4789-3825, Meldrum, FC orcid.org/0000-0001-9243-8517 and Christenson, HK orcid.org/0000-0002-7648-959X (2017) Observing the Formation of Ice and Organic Crystals in Active Sites. Proceedings of the National Academy of Sciences, 114 (5). pp. 810-815. ISSN 0027-8424
Abstract
Heterogeneous nucleation is vital to a wide range of areas as diverse as ice nucleation on atmospheric aerosols and the fabrication of high-performance thin films. There is excellent evidence that surface topography is a key factor in directing crystallization in real systems; however, the mechanisms by which nanoscale pits and pores promote nucleation remain unclear. Here, we use natural cleavage defects on Muscovite mica to investigate the activity of topographical features in the nucleation from vapor of ice and various organic crystals. Direct observation of crystallization within surface pockets using optical microscopy and also interferometry demonstrates that these sharply acute features provide extremely effective nucleation sites and allows us to determine the mechanism by which this occurs. A confined phase is first seen to form along the apex of the wedge and then grows out of the pocket opening to generate a bulk crystal after a threshold saturation has been achieved. Ice nucleation proceeds in a comparable manner, although our resolution is insufficient to directly observe a condensate before the growth of a bulk crystal. These results provide insight into the mechanism of crystal deposition from vapor on real surfaces, where this will ultimately enable us to use topography to control crystal deposition on surfaces. They are also particularly relevant to our understanding of processes such as cirrus cloud formation, where such topographical features are likely candidates for the “active sites” that make clay particles effective nucleants for ice in the atmosphere.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016, National Academy of Sciences . This is an author produced version of a paper published in Proceedings of the National Academy of Sciences. Uploaded in accordance with the publisher's self-archiving policy. In order to comply with the publisher requirements the University does not require the author to sign a non-exclusive licence for this paper. |
Keywords: | nucleation; confinement; topography; pores; active sites |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Inorganic Chemistry (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Molecular & Nanoscale Physics |
Depositing User: | Symplectic Publications |
Date Deposited: | 22 Dec 2016 11:21 |
Last Modified: | 12 Dec 2024 15:00 |
Published Version: | https://doi.org/10.1073/pnas.1617717114 |
Status: | Published |
Publisher: | National Academy of Sciences |
Identification Number: | 10.1073/pnas.1617717114 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:109807 |