Blinking of colloidal single crystals in aqueous suspensions of monodisperse colloidal silica spheres

Abstract

Abstract Close-up color photographs are taken of the blinking of small-sized (from several to several tens of micrometers) single crystals (or “crystallites”), which is due to translational and rotational Brownian movement, in a colloidal suspension of monodisperse silica spheres (110 nm in diameter). The blinking phenomenon of the crystallites continues for a long period, more than 24 h, and resembles the blinking lights on a Christmas tree. At one moment small crystallites seem to appear and in the next moment they disappear. Again, new crystallites appear in other places. The lifetimes of the crystallites are several seconds at room temperature and become shorter with rising suspension temperature. The blink occurs rapidly for colloidal suspensions very close to the critical concentration of melting nd for suspensions containing small amounts of foreign salt and/or aqueous-alcohol mixtures. The reason for the blinking phenomenon is ascribed to the rotational and translational movement of crystallites, which are surrounded in phase equilibrium with a liquid-like structure of suspension. Reflection spectra for suspensions exhibiting crystallites and their blinking are taken.