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Abstract: We compare the behavior of a new two-dimensional aqueous colloidal modelsystem with a simple numerical treatment. To the first order the attractiveinteraction between the colloids induced by an in-plane rotating ac electricfield is dipolar, while the charge stabilization leads to a shorter ranged,Yukawa-like repulsion. In the crystal-like -rafts- formed at sufficient fieldstrengths, we find quantitative agreement between experiment and Monte Carlosimulation, except in the case of strongly interacting systems, where the welldepth of the effective potential exceeds 250 times the thermal energy. The-lattice constant- of the crystal-like raft is located approximately at theminimum of the effective potential, resulting from the sum of the Yukawa anddipolar interactions.The experimental system has display applications, owing tothe possibility of tuning the lattice spacing with the external electric field.Limitations in the applied field strength and relative range of theelectrostatic interactions of the particles result in a reduction in tunablelattice spacing for small and large particles, respectively. The optimalparticle size for maximizing the lattice spacing tunability was found to bearound 1000 nm.



Author: Nils Elsner, C. Patrick Royall, Brian Vincent, David RE Snoswell

Source: https://arxiv.org/



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