Density fluctuations during crystallization of colloids

Long-wavelength density fluctuations are recorded by small-angle light scattering during the crystallization of hard colloidal spheres. Measured structure factors show approximate scaling with a peak at finite scattering vectors. The time dependences of the peak intensity and the wave vector clearly reveal two different crystallization regimes. For samples near the melting density, we find diffusion-limited growth at small times and Lifshitz-Slyozov ripening at large times. Growth exponents in the ripening process seem to increase for higher densities. All measurements demonstrate a strong coupling of the observed conserved density parameter to the nonconserved crystal-order parameter.