Ultra-small-angle neutron scattering studies of artificial lattices

Ultra-small-angle neutron scattering (USANS) with the use of perfect silicon crystals provides a resolution of the order of 10⁻⁵ Å⁻¹ in reciprocal space, which corresponds to μrad in scattering angles and μm structures in real space. From small-angle scattering by artificial lattices follows a unique test procedure for the related devices and techniques. Corresponding measurements were performed at the USANS facilities of the Atominstitut in Vienna and of the S18 instrument at the ILL. We observed diffraction patterns from samples being periodically structured in one and two dimensions. These measurements take advantage of the extended coherence function of the set-up and the high quality of the manufactured silicon sample lattices. Due to these characteristics up to 50 interference orders were obtained at the S18 instrument. Scattering from two-dimensional periodic structures was observed for different orientations of the sample which shows characteristic diffraction maps in reciprocal space.