DMR-9501865 Ackerson Experimental and modeling studies directed toward understanding the collective behavior of strongly interacting spherical particle systems will be carried out. Experiments will exploit the large length and time scales characteristic of colloidal suspensions of polymer spheres to probe equilibrium and nonequilibrium collective properties such as melting, crystal nucleation and growth, shear-induced melting and rheology. Experimental techniques include optical microscopy and digital image analysis, static and quasielastic light scattering, and x-ray diffraction. The modeling will focus on exploring the roles of geometric and topological defects on liquid structure, equilibrium melting, and shear-induced melting. %%% Systems of interacting spherical particles (colloids) are of fundamental interest in condensed matter physics. They are the simplest way to exhibit the still poorly understood melting-crystallization transition. Colloids exhibit the unique combination of softness of interaction, slowness in motion, and large spacing between particles that enables their effective use in the study of spherical particle behavior. Experiments involving a variety of optical techniques will be combined with model calculations to study recrystallization and glass formation as well as the importance of structural defects. ***
