The process of colloidal crystallization has already been separately investigated by light scattering measurements of the crystalline order (Bragg peaks) and of long-ranged density fluctuations (small-angle scattering). We present the first simultaneous small-and large-angle light scattering experiment. Our measurements have been performed on hard-sphere colloids of different particle densities. We show results for the temporal evolution of crystallization and find two distinct regimes: homogeneous nucleation and diffusion-or reaction-limited growth at early times, followed by ripening of the Lifshitz-Slyozov or Lifshitz-AUen-Cahn type. To our preliminary experience, we can already state that the results are always consistent in both partial experiments.
Applying static light scattering experiments, we characterize colloidal particles that are used as model hard-sphere systems in experiments investigating their crystallization kinetics. The particles comprise of a compact core of poly(methyl methacrylate) and short polymer hairs grafted onto the surface. We use a contrast variation procedure to determine the refractive index variation within the particles and observe that one component of the binary mixture used as a solvent penetrates the particles and masks completely the small polymer hairs. Making use of the determined refractive index variation, we obtain the average particle radius and its polydispersity from measurements of the particle form factor close to its minimae. The scattered intensity has been corrected carefully for multiple scattering contributions applying dynamic light scattering measurements with multiple scattering decorrelation. We obtain a mean particle radius of &Rmacr;=435+/-4 nm and a polydispersity of sigma=2.5%, a resolution that has not been achieved with light scattering experiments before.
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