X-ray diffraction of photonic colloidal single crystals

We have resolved a great number of Bragg peaks of photonic colloidal single crystals by synchrotron small angle X-ray scattering (SAXS). We find that charge-stabilized colloids form face-centered cubic crystals at all densities up to ̃60 vol %. The colloidal particles are highly ordered on their lattice sites, which confirms that these self-organizing materials are suitable building blocks for optical photonic matter. The experiments demonstrate that synchrotron SAXS with two-dimensional detection is a powerful tool to study systems with length scales comparable to optical wavelengths.