Statistics of a colloidal fluid-fluid interface (AGGREGATION CH 8)

Abstract

We report on measurements made by laser scanning confocal microscopy on the statistics of the interface of phase separated colloid-polymer systems. Due to the Brownian character of the process, the statistics vary with the chosen measurement interval Δt. We focus in particular on the residence times of capillary waves above a given height h and on the waiting times in between such fluctuations. The discrete scanning times are a practical cutoff and we are able to measure the waiting time as a function of this cutoff. The measurement interval dependence of the observed waiting and residence times turns out to be solely determined by the time dependent height-height correlation function g(t). The accompanying distributions of time intervals are predictable in terms of g(t) as well. We find excellent agreement between the theory presented here and the experiments.