Structure and kinetics of heteroaggregation in binary dipolar monolayers

Abstract

We present an experimental study of the kinetic and structural aspects ofheteroaggregation in binary dipolar monolayers. Particles of the two components of thesystem have oppositely oriented dipole moments constrained to be perpendicular to theplane of motion. We show experimentally that growing clusters have chain-likemorphology with a crossover to branched structures, whose fractal dimension isequal to that of self-avoiding random walks and reaction-limited cluster–clusteraggregation, respectively. The average cluster size and number of clusters havea power-law behavior as a function of time, in which the dynamic exponentsdepend on the concentration. Our experiments revealed a clear discriminationbetween clusters of an even and odd number of particles, i.e. the concentrationof even-sized clusters has a much faster decay with time than that of the oddones; furthermore, at a given time the concentration of clusters shows even–oddoscillations.