ABSTRACT
Fluctuations of the interface between coexisting colloidal fluid phases have been measured with confocal microscopy. Due to a very low surface tension, the thermal motions of the interface are so slow that a record can be made of the positions of the interface. The theory of the interfacial height fluctuations is developed. For a host of correlation functions, the experimental data are compared with the theoretical expressions. The agreement between theory and experiment is remarkably good.
ABSTRACT
On-lattice Monte Carlo simulations of colloidal random-stacking hard-sphere colloidal crystals are presented. The model yields close-packed crystals with random-stacking hexagonal structure. We find a significant amount of in-plane stacking disorder, which slowly anneals in the course of the simulation. The in-plane stacking disorder leads to lateral broadening of the stacking-disorder-induced Bragg rods. It is found that not only the scattering intensity, but also the width is modulated along the Bragg rods.
ABSTRACT
Stokes drag on the (sub)micrometre scale plays a key role in phenomena ranging from Brownian motion to the rheology of particulate suspensions. We report the first measurement of the direction dependent Stokes drag in a nematic liquid crystal of colloidal rods, where the viscous forces are of equal importance to the elastic forces. By tracking a sedimenting sphere with combined fluorescence confocal microscopy and polarization microscopy we find that the Stokes drag for motion along the director is two times larger than for motion perpendicular to the director. This brings the unique viscoelastic properties of a colloidal liquid crystal into focus.
