Diffusion in concentrated colloidal suspensions and glasses

The well established analogy between colloidal suspensions and atomic fluid s has been extended to the glass transition problem in the past few years. Colloids have become the ideal test case for checking glass transition theo ries; this was due to the possibility of modeling hard spheres with colloid al dispersions. Significant progress has also been made in instrumentation, especially in the development of light-scattering techniques allowing mode rately turbid and nonergodic samples to be analyzed. Mode coupling theory h as become a paradigm not only for the glass transition, but also for the un derstanding of dynamics in highly concentrated colloidal dispersions where crystallization is suppressed. Application of advanced optical microscopy t echniques in combination with computer simulation has started to provide a deeper insight into the physics of colloidal suspensions at volume fraction s above freezing.