The equilibrium intrinsic crystal-liquid interface of colloids

TL;DR

This study uses confocal microscopy to directly visualize and characterize the intrinsic crystal-liquid interface in colloidal suspensions, revealing a sharply defined interface with a width slightly larger than a particle diameter.

Contribution

First direct experimental visualization of an equilibrated crystal-liquid interface in colloids, with detailed measurements of its structure and dynamics.

Findings

Intrinsic interface width is about 1.5 to 2.4 times the particle diameter.

Capillary waves roughen the surface but do not obscure the intrinsic interface.

Different measurement methods yield slightly different interface widths.

Abstract

We use confocal microscopy to study an equilibrated crystal-liquid interface in a colloidal suspension. Capillary waves roughen the surface, but locally the intrinsic interface is sharply defined. We use local measurements of the structure and dynamics to characterize the intrinsic interface, and different measurements find slightly different widths of this interface. In terms of the particle diameter $d$, this width is either $1.5d$ (based on structural information) or $2.4d$ (based on dynamics), both not much larger than the particle size. This work is the first direct experimental visualization of an equilibrated crystal-liquid interface.