Formation of meso-structures in colloidal monolayers

Ghezzi, Fabio; Earnshaw, J. C.

doi:10.1088/0953-8984/9/37/004

Cited by 104 publications

(136 citation statements)

References 16 publications

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“…Examples include 2D crystallization [3,4] and grain-boundary fluctuations [5], crystal sublimation [6] and colloidal glasses [7,8], interactions between similarly charged particles [9][10][11][12], and Brownian dynamics at liquid interfaces [13][14][15][16][17]. They offer many advantages over atomic or molecular fluids, because the dynamics of the particles are slower and can be tracked at the single-particle level with video microscopy [18].…”

Section: Introductionmentioning

confidence: 99%

Colloidal dynamics over a tilted periodic potential: Nonequilibrium steady-state distributions

Lai

Ackerson

et al. 2015

Phys. Rev. E

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We report a systematic study of the effects of the external force F on the nonequilibrium steady-state (NESS) dynamics of the diffusing particles over a tilted periodic potential, in which detailed balance is broken due to the presence of a steady particle flux. A tilted two-layer colloidal system is constructed for this study. The periodic potential is provided by the bottom-layer colloidal spheres forming a fixed crystalline pattern on a glass substrate. The corrugated surface of the bottom colloidal crystal provides a gravitational potential field for the top-layer diffusing particles. By tilting the sample at an angle θ with respect to the vertical (gravity) direction, a tangential component of the gravitational force F is applied to the diffusing particles. The measured NESS probability density function P ss (x,y) of the particles is found to deviate from the equilibrium distribution P (x,y) to a different extent, depending on the driving or distance from equilibrium. The experimental results are compared with the exact solution of the one-dimensional (1D) Smoluchowski equation and the numerical results of the 2D Smoluchowski equation. From the obtained exact solution of the 1D Smoluchowski equation, we develop an analytical method to accurately extract the 1D potential U 0 (x) from the measured P ss (x). This work demonstrates that the tilted periodic potential provides a useful platform for the study of forced barrier-crossing dynamics beyond the Arrhenius-Kramers equation.

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Section: Introductionmentioning

confidence: 99%

Colloidal dynamics over a tilted periodic potential: Nonequilibrium steady-state distributions

Lai

Ackerson

et al. 2015

Phys. Rev. E

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“…Even with neutral particles interacting solely via depletion forces, competition may arise as a consequence of mutual interactions between the depletants, which modify the interaction potential with respect to the simplest Asakura-Oosawa picture [1]. Structuring and pattern formation has also been seen in two dimensional systems [7,8], where the repulsion is likely to be due to dipole-dipole interactions between the particles at the surface. Together with these experimental studies, there has been significant theoretical interest in model colloidal systems exhibiting such competing interactions [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31].…”

Section: Introductionmentioning

confidence: 99%

Theory for the phase behaviour of a colloidal fluid with competing interactions

Archer

Ionescu

Pini

et al. 2008

J. Phys.: Condens. Matter

111

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We study the phase behaviour of a fluid composed of particles which interact via a pair potential that is repulsive for large inter-particle distances, is attractive at intermediate distances and is strongly repulsive at short distances (the particles have a hard core). As well as exhibiting gasliquid phase separation, this system also exhibits phase transitions from the uniform fluid phases to modulated inhomogeneous fluid phases. Starting from a microscopic density functional theory, we develop an order parameter theory for the phase transition in order to examine in detail the phase behaviour. The amplitude of the density modulations is the order parameter in our theory. The theory predicts that the phase transition from the uniform to the modulated fluid phase can be either first order or second order (continuous). The phase diagram exhibits two tricritical points, joined to one another by the line of second order transitions.

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“…There is much interest in the basic statistical physics of systems with such interactions, which play a role in gravitational collapse, two-dimensional elasticity, chemotactic collapse, quantum fluids, and atomic clusters [14]. One proposed realization are colloidal particles trapped at an interface [15] that experience screened, long-range attractions due to capillary fluctuations of the interface [16]. The attractive interactions then correspond to Newtonian gravity in two dimensions.…”

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confidence: 99%

Self-Assembly of Colloidal Molecules due to Self-Generated Flow

2017

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The emergence of structure through aggregation is a fascinating topic and of both fundamental and practical interest. Here we demonstrate that self-generated solvent flow can be used to generate longrange attractions on the colloidal scale, with sub-pico Newton forces extending into the millimeterrange. We observe a rich dynamic behavior with the formation and fusion of small clusters resembling molecules, the dynamics of which is governed by an effective conservative energy that decays as 1/r. Breaking the flow symmetry, these clusters can be made active.Colloidal particles acting as "big" artificial atoms have been instrumental in studying microscopic processes in condensed matter, from the kinetics of crystallization [1] to the vapor-liquid interface [2]. Due to their size, colloidal particles are observable directly in real space. Moreover, interactions are widely tunable, ranging from hard spheres to long-range repulsive, short-range attractive, and dipolar [3,4]. Consequently, colloidal particles can be assembled into a multitude of different structures: from clusters [5][6][7] and stable molecules [8,9] composed of a few particles to extended bulk structures like ionic binary crystals [10]. In addition, self-assembly into useful superstructures can be controlled by factors such as confinement [11] and particle shape [12], which make colloids a versatile and fascinating form of matter [13].What is still missing are truly long-range attractions of like-charged (or uncharged) identical colloidal particles. There is much interest in the basic statistical physics of systems with such interactions, which play a role in gravitational collapse, two-dimensional elasticity, chemotactic collapse, quantum fluids, and atomic clusters [14]. One proposed realization are colloidal particles trapped at an interface [15] that experience screened, long-range attractions due to capillary fluctuations of the interface [16]. The attractive interactions then correspond to Newtonian gravity in two dimensions. Complex patterns are also known to arise for bacteria due to longrange chemotactic interactions [17]. Critical long-range Casimir forces have been reported for colloidal particles in a binary solvent [18], which are tunable by temperature and surface chemistry. Finally, a recent theoretical proposal are catalytically active colloidal particles that interact through producing or consuming chemicals [19,20]. For simple diffusion the concentration profile of a chemical decays as inverse distance, implying long-range interactions that can be tuned through activity (how chemicals are produced or consumed) and mobility (how particles react to gradients).Here, we implement long-range attractions through hydrodynamic flows coupling suspended particles [21,22]. We report on experiments using spherical ion exchange resin particles sedimented to the negatively charged substrate. The particles have diameters of 15 µm, for which Brownian diffusion is practically negligible on the experimental time scale. They interact due to self-genera...

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Formation of meso-structures in colloidal monolayers

Cited by 104 publications

References 16 publications

Colloidal dynamics over a tilted periodic potential: Nonequilibrium steady-state distributions

Colloidal dynamics over a tilted periodic potential: Nonequilibrium steady-state distributions

Theory for the phase behaviour of a colloidal fluid with competing interactions

Self-Assembly of Colloidal Molecules due to Self-Generated Flow

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