A holographic image of the atomic arrangement in a PdH0.78 single crystal was recorded using spherical neutron waves generated by incoherent neutron-proton scattering (“internal source concept”). The resolution is sufficient to show the positions of single atomic nuclei on their respective lattice sites despite the delocalization of protons due to the weak bonding of hydrogen dissolved in palladium metal. Ways to overcome problems in the reconstruction of atomic positions related to the highly unfavorable sample shape are discussed. The technique offers possibilities for the investigation of various materials containing substantial amounts of hydrogen.

Poly(N‐vinylcaprolactam) (PVCL) is a synthetic analogue of biomolecules (enzymes, proteins). It demonstrates a specific hydration and undergoes a coil–globule transition. The PVCL–D2O system (PVCL mass M = 106) has been investigated by small‐angle neutron scattering (SANS) at T = 296–316 K to identify the structural features of the collapse at concentration C = 0.5 wt% near the threshold of the coil overlap. (The collapse leads to the segregation of the phase enriched with polymer at T > 305 K). The SANS experiments at q = 0.1–5 nm−1 (scales from monomer unit to globule gyration radius RG≃ 16 nm) have revealed a stretched coil–globule transformation in the range 305–309 K. Using high‐resolution SANS (q = 0.002–0.02 nm−1) the globule association to form fractal structures (sponge‐like) of surface dimension DF≃ 2.4–2.6 was examined. The coexistence of globules and disordered chains (regions ∼5–10 nm) was found. The growth of the content of globular phase was induced by the conformational transition in disordered molecular fragments from coiled (dimension D≃ 1.8) to stretched chains (D≃ 1.2).

We demonstrate that neutron holography permits us to extend the determination of atomic positions beyond nearest neighbors at least up to the fourth neighboring shell around cadmium probe atoms alloyed into a lead crystal. The accuracy achieved is sufficient to allow quantitative determination of displacements of atoms due to elastic distortions induced by impurity atoms. The atomic positions derived from the holographic data are in good agreement with those expected theoretically due to Friedel oscillations in this system. In addition, the atomic positions are in qualitative agreement with results obtained in an independent experiment studying the diffuse distortion scattering around Bragg peaks.

Summary: Protonated star-shaped polystyrenes with single and double fullerene C 60 core and the hybrid stars with pairs of polar and non-polar arms (tertbuthylmetacrylate, polystyrene) have been studied in deuterated toluene (20 8C) by small-angle neutron scattering at low and moderate polymer concentrations (c 1 $ 1 g/dl, c 2 $ 3-6 g/dl) to evaluate the peculiarities of fullerene centre action on polymers selfassembly in solutions. As we found, the cores composed of two fullerenes, linked via Si(CH 3 ) 2 -bridge, induce stars' anisotropic interactions and association into chain-like structures (correlation radius $400-600 nm). Meanwhile, the single-core stars of polystyrene and hybrids organize globular clusters (size $ 10 3 nm) those geometry do not change significantly by polymer content variation.

Neutron scattering device dedicated to neutron holography experiments is described. The device is operating at a constant wavelength prepared by a double focusing monochromator. It is equipped by highly efficient shielding, proper collimator, Eulerian cradle, monitor detector, gamma-ray, and neutron detectors as well. Relevant software serves as control for the measurement and data collection. The harmonized application of the components enumerated above makes our device extremely efficient and unparalleled. Two atomic resolution neutron holographic experiments carried out illustrate the efficiency and power of the instrument.