ELECTRIC-FIELD-INDUCED PATTERN-FORMATION IN INTERFACIAL METAL COLLOIDFILMS

First results on electric field induced aggregation in a novel colloid al film are presented. The aggregate appears as a dark structure on th e shiny background of the metallic colloidal film that forms at the in terface between two immiscible liquids. A variety of shapes are observ ed, ranging from compact circular, to highly ramified dendritic ones, depending on control parameters such as voltage and chemical compositi on. The aggregation process was investigated for a wide range of param eters by video photography and subsequent pattern analysis, as well as by Auger spectroscopic measurements of dried samples. A new type of m echanism - a combination of electroaggregation of the colloid particle s and electrodeposition of metal ions - is proposed to account for the observations.