title: Band formation in mixtures of oppositely charged colloids driven by an ac electric field.
abstract: We present experiments on pattern formation in a Brownian system of oppositely charged colloids driven by an ac electric field. Using confocal laser scanning microscopy we observe complete segregation of the two particle species into bands perpendicular to a field of sufficient strength when the frequency is in a well-defined range. Because of its Brownian nature the system spontaneously returns to the equilibrium mixture after the field is turned off. We show that band formation is linked to the time scale associated with collisions between particles moving in opposite directions.
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands. t.vissers@uu.nl
authors.forename: Teun
authors.initials: T
authors.lastname: Vissers
authors.forename: Alfons
authors.initials: A
authors.lastname: van Blaaderen
authors.forename: Arnout
authors.initials: A
authors.lastname: Imhof
mesh_terms: D003102:Colloids / Q000737:chemistry*; D004560:Electricity; D018613:Microscopy, Confocal; D019904:Polymethyl Methacrylate / Q000737:chemistry
chemical_list: D003102:Colloids; D019904:Polymethyl Methacrylate