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.