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Dissipating Step Bunches during Crystallization under Transport ControlIn studies of crystal formation by the generation and spreading of layers, equidistant step trains are considered unstable---bunches and other spatiotemporal patterns of the growth steps are viewed as ubiquitous. We provide an example to the opposite. We monitor the spatiotemporal dynamics of steps and the resulting step patterns during crystallization of the proteins ferritin and apoferritin using the atomic force microscope. The variations in step velocity and density are not correlated, indicating the lack of a long-range attraction between the steps. We show that (i) because of its coupling to bulk transport, nucleation of new layers is chaotic and occurs at the facet edges, where the interfacial supersaturation is higher; (ii) step bunches self-organize via the competition for supply from the solution; and, (iii) bunches of weakly interacting steps decay as they move along the face. Tests by numerical modeling support the conclusions about the mechanisms underlying our observations. The results from these systems suggest that during crystallization controlled by transport, with weakly or noninteracting growth steps, the stable kinetic state of the surface is an equidistant step train, and step bunches only arise during nucleation of new layers. Since nucleation only occurs at a few sites on the surface, the surface morphology may be controllably patterned or smoothened by locally controlling nucleation.
Document ID
20050070719
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Lin, Hong
(Alabama Univ. Huntsville, AL, United States)
Yau, S.-T.
(Hunter Coll. New York, NY, United States)
Vekilov, Peter, G.
(Houston Univ. TX, United States)
Date Acquired
August 22, 2013
Publication Date
March 25, 2003
Publication Information
Publication: Physical Review E (Statistical, Nonlinear, and Soft Matter Physics)
Volume: 67
Subject Category
Solid-State Physics
Funding Number(s)
CONTRACT_GRANT: NAG8-1854
Distribution Limits
Public
Copyright
Other

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