Simple models for two-dimensional tunable colloidal crystals in rotating ac electric fields

Elsner, Nils; Royall, C. Patrick; Vincent, Brian; Snoswell, David R. E.

doi:10.1063/1.3115641

Cited by 50 publications

(58 citation statements)

References 35 publications

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“…Indeed, a rotating inplane field generates, on averaging over time, an inverted dipolar pair interaction with in-plane attraction and repulsion along the rotation axis. 11,12 Therefore, the structures induced by planar rotating fields are markedly different from those observed in a constant and homogeneous field, which supports the formation of field-aligned chains (low densities) [13][14][15] and bulk crystals.…”

Section: 3mentioning

confidence: 78%

“…7,8 A classical example in this context, first discussed by Martin et al, 9 is systems of paramagnetic (or polarizable) spherical particles in magnetic (electric) fields rotating in a plane. For sufficient field strength, both experiment and computer simulations [9][10][11] reveal the formation of layers in the field plane, i.e., a spatial symmetry breaking induced by the rotating field. Indeed, a rotating inplane field generates, on averaging over time, an inverted dipolar pair interaction with in-plane attraction and repulsion along the rotation axis.…”

Section: 3mentioning

confidence: 99%

“…This is 1-2 orders of magnitude larger than the frequencies used in the literature. 4,11 Ferrocolloidal particles, which have permanent dipoles (such as the ones considered here), are often much smaller with sizes of about 10 nm. In that case, u * 0 ¼ 10 corresponds to a driving frequency of about 1 GHz.…”

Section: à3mentioning

confidence: 99%

“…In many experiments involving rotating fields, the size of the (typically superparamagnetic) particles considered is about 1 mm. 4,11 A driving frequency of u * 0 ¼ 10 (which is well within the layered domain) then corresponds to an actual frequency of about 10 kHz if we assume room temperature (T ¼ 293 K) and a mass density of 5 g cm…”

mentioning

confidence: 99%

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Pattern formation of dipolar colloids in rotating fields: layering and synchronization

Jäger

Klapp

2011

Soft Matter

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We report Brownian dynamics (BD) simulation and theoretical results for a system of spherical colloidal particles with permanent dipole moments in a rotating magnetic field. Performing simulations at a fixed packing fraction and dipole coupling parameter, we construct a full non-equilibrium phase diagram as a function of the driving frequency (u 0 ) and field strength (B 0 ). This diagram contains both synchronized states, where the individual particles follow the field with (on average) constant phase difference, and asynchronous states. The synchronization is accompanied by layer formation, i.e., by spatial symmetry-breaking, similar to systems of induced dipoles in rotating fields. In the permanent dipole case, however, too large u 0 yields a breakdown of layering, supplemented by complex changes of the single-particle rotational dynamics from synchronous to asynchronous behavior. We show that the limit frequencies u c can be well described as a bifurcation in the nonlinear equation of motion of a single-particle rotating in a viscous medium. Finally, we present a simple density functional theory, which describes the emergence of layers in perfectly synchronized states as an equilibrium phase transition.

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Section: 3mentioning

confidence: 78%

Section: 3mentioning

confidence: 99%

Section: à3mentioning

confidence: 99%

mentioning

confidence: 99%

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Pattern formation of dipolar colloids in rotating fields: layering and synchronization

Jäger

Klapp

2011

Soft Matter

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“…For example, field-matter interactions constitute processes in which energy is exchanged with a reacting system. These interactions lead to emergent and controllable behavior in assembly phenomena, [27][28][29][30] organic synthesis, 31 protein folding, 32 the detection of DNA, 33 and photodissociation. 34 Knowledge of the mechanism by which these interactions mediate reactive flow provides a methodological tool in the design of molecular devices with unique functionality.…”

Section: Introductionmentioning

confidence: 99%

Chemical reactions induced by oscillating external fields in weak thermal environments

Craven

Bartsch

Hernandez

2015

The Journal of Chemical Physics

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Chemical reaction rates must increasingly be determined in systems that evolve under the control of external stimuli. In these systems, when a reactant population is induced to cross an energy barrier through forcing from a temporally varying external field, the transition state that the reaction must pass through during the transformation from reactant to product is no longer a fixed geometric structure, but is instead timedependent. For a periodically forced model reaction, we develop a recrossing-free dividing surface that is attached to a transition state trajectory [T. Bartsch, R. Hernandez, and T. Uzer, Phys. Rev. Lett. 95, 058301 (2005)]. We have previously shown that for single-mode sinusoidal driving, the stability of the timevarying transition state directly determines the reaction rate [G. T. Craven, T. Bartsch, and R. Hernandez, J. Chem. Phys. 141, 041106 (2014)]. Here, we extend our previous work to the case of multi-mode driving waveforms. Excellent agreement is observed between the rates predicted by stability analysis and rates obtained through numerical calculation of the reactive flux. We also show that the optimal dividing surface and the resulting reaction rate for a reactive system driven by weak thermal noise can be approximated well using the transition state geometry of the underlying deterministic system. This agreement persists as long as the thermal driving strength is less than the order of that of the periodic driving. The power of this result is its simplicity. The surprising accuracy of the time-dependent noise-free geometry for obtaining transition state theory rates in chemical reactions driven by periodic fields reveals the dynamics without requiring the cost of brute-force calculations.

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Generating Lithographically‐Defined Tunable Printed Structural Color

Michaelis¹,

Snoswell²,

Bell³

et al. 2013

Adv Eng Mater

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A tunable method for generating non-fading printed structural color is demonstrated. The process involves the rapid generation and self-assembly of particle strings, using standard colloidal polymeric particles and AC electric fields, with no requirement for a ??wash-out?? step. By using an organic UV-curable medium, we demonstrate that these tunable structures can be permanently fixed in a flexible polymer matrix and thus are suitable for printing applications.Peer reviewe

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Simple models for two-dimensional tunable colloidal crystals in rotating ac electric fields

Abstract: Articles you may be interested inFormation and structure of colloidal halos in two-dimensional suspensions of paramagnetic particles

Cited by 50 publications

References 35 publications

Pattern formation of dipolar colloids in rotating fields: layering and synchronization

Pattern formation of dipolar colloids in rotating fields: layering and synchronization

Chemical reactions induced by oscillating external fields in weak thermal environments

Generating Lithographically‐Defined Tunable Printed Structural Color

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