Two-dimensional Fourier analysis and quasielastic light-scattering measurements of colloid crystals

Two-dimensional (2D) Fourier transformation was carried out for particle distribution in highly purified polymer latex suspensions by use of a digital-image-processing system. The particle distributions were photographed by an optical microscope for larger particles (> approximately 0.2 μm in diameter) at various temperatures and particle charges. The interparticle distance (2$D_{\mathrm{expt}}$) calculated from the halo pattern in the Fourier image hardly changed with increasing temperature (i.e., with decreasing dielectric constant for water), and decreased with particle charges.