Structure and dynamics of a layer of sedimented particles

Adar Sonn-Segev, Jerzy Bławzdziewicz, Eligiusz Wajnryb, Maria L. Ekiel-Jezewska, Haim Diamant, Yael Roichman

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6 Scopus citations


We investigate experimentally and theoretically thin layers of colloid particles held adjacent to a solid substrate by gravity. Epifluorescence, confocal, and holographic microscopy, combined with Monte Carlo and hydrodynamic simulations, are applied to infer the height distribution function of particles above the surface, and their diffusion coefficient parallel to it. As the particle area fraction is increased, the height distribution becomes bimodal, indicating the formation of a distinct second layer. In our theory, we treat the suspension as a series of weakly coupled quasi-two-dimensional layers in equilibrium with respect to particle exchange. We experimentally, numerically, and theoretically study the changing occupancies of the layers as the area fraction is increased. The decrease of the particle diffusion coefficient with concentration is found to be weakened by the layering. We demonstrate that particle polydispersity strongly affects the properties of the sedimented layer, because of particle size segregation due to gravity.

Original languageEnglish
Article number074704
JournalJournal of Chemical Physics
Issue number7
StatePublished - Aug 21 2015


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