Forma, Vol. 17 (No. 2), pp. 141-153, 2002
Original Paper

Spectroscopy of Giant Colloidal Crystals

Tsuneo Okubo* and Akira Tsuchida

Department of Applied Chemistry, Gifu University, Gifu 501-1193, Japan
*E-mail address:

(Received May 9, 2002; Accepted June 14, 2002)

Keywords: Colloidal Crystal, Reflection Spectra, Electrical Double Layer, Crystallization, Electro-Optic Effect

Abstract. Colloidal crystals are the suspensions in which colloidal particles distribute regularly as atoms and molecules do in metals and protein crystals. Giant colloidal crystals invented by the authors emit brilliant iridescent light by the Bragg diffraction and are quite beautiful. In this article recent works in our laboratory on the spectroscopic study of the crystallization kinetics, structural and dynamic properties and the electro-optic effects of giant colloidal crystals have been discussed. Formation of giant colloidal single crystals is due to the electrostatic intersphere "repulsion" and to the highly expanded electrical double layers surrounding colloidal spheres. Spectroscopic measurements, e.g., transmitted light spectrum, reflection spectrum and static and dynamic light scattering reveals the importance of the electrical double layers for colloidal crystallization. The substantial acceleration effect of microgravity in the alloy crystallization supports that the colloidal crystallization takes place by the condition whether the maximum packing density is achieved or not for a given ratio of the sphere sizes including surrounding electrical double layers.

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