Experimental Study of Two-Beam X-Ray Diffractometry Using Synchrotron Radiation

Crystallography Reports - A new scheme of two-beam X-ray diffractometry on the “X-Ray Crystallography and Physical Materials Science” (XCPM) beamline at the Kurchatov Synchrotron...     

Laser-Synchrotron Facility of the National Research Centre “Kurchatov Institute”

Crystallography Reports - The laser-synchrotron facility (LSF) of the National Research Centre “Kurchatov Institute” (NRC KI) is a unique research complex that combines unprecedented...     

Molecular dynamics of ion exchangers SG-1M and SGK-7 determined from neutron spectroscopy data

The inelastic neutron scattering spectra of samples of ion exchangers SG-1M and SGK-7, both “dry” and hydrated in heavy water, have been recorded in the temperature range 220–363 K on the time-of-flight spectrometers of the Kurchatov Institute and the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research. With an increase in the degree of hydration and sample temperature, the inelastic scattering spectra exhibit changes in the region of low-frequency vibrations, whereas the region of torsional vibrations of methyl groups remains relatively stable. Generalized frequency distributions are obtained for the samples studied. The effect of hydration and temperature on the noted microdynamic characteristics is discussed.     

Structural studies of the lipid membranes at the Siberia-2 synchrotron radiation source

Lipid membranes are a subject of contemporary interdisciplinary studies at the junction of biology, biophysics, pharmacology, and bionanotechnology. The results of the structural studies of several types of lipid membranes by the lamellar and lateral diffraction of X-ray synchrotron radiation are presented. The experiments were performed at the Mediana and DICSI stations of the Siberia-2 synchrotron radiation source at the Russian Research Center Kurchatov Institute. The data obtained are compared with the results of studying lipid membranes at the small-angle scattering beamlines D22 and D24 at LURE (France) and at the A2 beamline at DESY (Germany). The parameters of the DICSI station are shown to meet the basic requirements for the structural study of lipid systems, which are of fundamental and applied interest.     

Kurchatov Synchrotron Radiation Source Upgrade Project

Crystallography Reports - The National Research Centre “Kurchatov Institute” has started a project aimed at upgrading the synchrotron radiation source. On the basis of the existing...     

The Provenance Study of the Raw Materials of the Ancient Terracotta Found near the Crimean Bridge: Natural-Science Approach

Crystallography Reports - The paste of a series of ceramic products from the Black Sea and Mediterranean regions have been studied at the National Research Centre “Kurchatov Institute”...     

From gene to structure: The protein factory of the NBICS Centre of Kurchatov Institute

The Protein Factory was established at the Centre for Nano, Bio, Info, Cognitive, and Social Sciences and Technologies (NBICS Centre) of the National Research Centre “Kurchatov Institute” in 2010. The Protein Factory, together with the Centre for Synchrotron Radiation and Nanotechnology, promote research on structural biology. This paper presents the technology platforms developed at the Protein Factory and the facilities available for researchers. The main projects currently being performed at the Protein Factory are briefly described.     

Determination of preferential molecular orientation in porphyrin-fullerene dyad ZnDHD6ee monolayers by the X-ray standing-wave method and X-ray reflectometry

Monolayers of porphyrin-fullerene dyad molecules with zinc atoms incorporated into the porphyrin ring (ZnDHD6ee) on the surface of aqueous subphase and on Si substrates have been investigated by the X-ray standing-wave method and X-ray reflectometry. The experiments have been performed under laboratory conditions and on synchrotron radiation sources (KMC-2 station of BESSY II (Berlin) and Langmuir station at the National Research Centre “Kurchatov Institute”). Depth distributions of Zn atoms and electron density in the monolayer film are calculated. On the basis of the analysis of these distributions, it is concluded that ZnDHD6ee dyad molecules in monolayers have preferential orientation. The data obtained indicate that the molecules in monolayer film retain their orientation when the monolayer is transferred from a liquid subphase surface onto a solid substrate.     

Numerical simulation of experimental resonance absorption spectra and diffraction of synchrotron radiation in yttrium iron garnet

Extended X-ray absorption fine-structure spectra of yttrium-iron garnet, measured near the absorption edges of iron and yttrium at the Kurchatov synchrotron radiation source are reported. Numerical simulation of the X-ray absorption near-edge structure of these spectra is performed and good agreement with the experimental data is obtained. It is shown theoretically that “forbidden” Bragg reflections can be observed near the absorption edges of iron and yttrium. The indices of these reflections are determined. The energy structure of the “forbidden” reflections 006 and 110 is calculated.     

Total external reflection X-ray fluorescence analysis of protein-metal ion interactions in biological systems

This paper presents the results of an investigation into hemoglobin-based protein films that were formed on a liquid surface. X-ray standing wave measurements were performed at the ID 10 beamline of the European Synchrotron Radiation Facility (ESRF) and at the Langmuir station of the Kurchatov Synchrotron Radiation Source. It was found that the ability of the protein to bind metal ions is substantially increased due to the conformational rearrangements of protein macromolecules caused by various damaging effects. The elemental composition of protein preparations, which were isolated from children and adults with chronic metabolic diseases accompanied by endogenous intoxication, was analyzed. The results of the investigations offer evidence that an increase in the ligand-binding properties of the protein molecules, which was observed in model experiments using protein films, is a common trait and corresponds to in vivo processes accompanying metabolic disturbances in the body.     

Investigation on low temperature thermoluminescence centres in Quartz

The present paper will help to understand the often investigated process of thermoluminescence of quartz which is of high complexity. A lot of traps exist in quartz crystals which compete with each other with respect to the trapping of charge carriers during the X-ray treatment. That is why a variety of processes takes place after X-irradiation at liquid nitrogen temperature (LNT) of quartz which complicate the phenomenology of low temperature thermoluminescence. This competition in the trapping process leads to the socalled “sensibilization” or “desensibilization” effects of thermoluminescence, respectively, which are described in this paper for the first time. This effect means the dependence of the LNT thermoluminescence intensity on a pre-irradiation dose applied at room temperature (RT). The influence of this pre-irradiation is understood assuming the saturation of competitive traps. This favours an enhanced trapping of charge carriers at LNT-(shallow) traps instead of the preferential trapping on the deep traps in the case of X-ray treatment of the as-grown crystal at LNT. To get the afore mentioned model we take into account not only thermoluminescence but also coloration, ir- and vuv-absorption measurements.     

Localized surface plasmon enhanced microcrystalline–silicon solar cells

A novel type of substrate named “Ag–SP substrate”, in which silver nanoparticles are incorporated, is introduced and utilized as a back reflector for hydrogenated microcrystalline-silicon solar cell in a substrate-type (n-i-p) configuration. Optical and morphological analyses of Ag–SP substrates fabricated with various sizes of silver nanoparticles are systematically performed. It is shown that silver nanoparticles in Ag–SP substrate structure can lead to significant scattering of light when their diameter increases up to 300 nm. Furthermore, the photocurrent of the solar cell fabricated on an Ag–SP substrate with RMS roughness as small as 16.5 nm and a proper lateral diameter (approximately 300 nm) of silver nanoparticles is improved as compared to that of the solar cell prepared on reference textured substrate with RMS roughness of 25.3 nm, owing to strong scattering of light by silver nanoparticles in the red-infrared region.     

Evaporite minerals succession

An explanation is given for the crystallization succession during sea-water evaporation, namely for the differences between the equilibrium solubility diagram of the marine-type system and the “solar diagram”: The magnesium ions are known to exist in sea-type solutions predominantly as hexaaqua complexes. Highest crystallization rates and lowest supersaturations required for nucleation should be exhibited by the magnesium salts, crystal structures of which incorporate unchanged hexaaqua magnesium complexes. For the salts with crystal structures in which the water molecules from the magnesium hexaaqua ions are partially or completely replaced by other ligands, the nucleations require high supersaturations and for this reason they do not appear in the “solar diagram”. This model is used to explain also some genetic pecularities of evaporite deposits: primary evaporite minerals are those which occur according to the “solar diagram” of crystallization. The evaporite minerals featuring in the equilibrium diagram and absent in the “solar diagram” occur in nature most frequently as secondary minerals.     

Information communication platform for the NBIC center at the Russian Research Center Kurchatov Institute

The problems of developing a unified information communication platform for the Nano-, Bio-, Info-, and Cognitive (NBIC) Technology Center at the Russian Research Center (RRC) Kurchatov Institute are considered. The distributed resources of the NBIC center are used based on grid technologies, which allow one to construct a distributed infrastructure on the basis of existing data transfer networks and computer equipment in accordance with the user’s requirements. This infrastructure makes it possible to uniformly offer combined computational resources for various scientific calculations and allows distant users to visually operate with very large amounts of data, high-resolution video streams, experimental equipment, and archival data sets.     

Role of the silica source on the geopolymerization rate

The synthesis of geopolymer-silica composites was achieved at room temperature to determine the role of the silica source (quartz or amorphous silica) on the polycondensation rate and the mechanical properties of synthesized materials. Then, samples with a composition range from 100% quartz to 100% amorphous silica were formed, compared and characterized by XRD, infrared spectroscopy, thermal analysis, SEM, and compression tests. The results give evidence that the increase of amorphous silica in the mixture favors the polycondensation reaction (i.e., “geopolymerization”) to form consolidated materials whereas quartz led to heterogeneous materials without cohesion. These facts are explained by the modification of the Si/Al ratio in the geopolymer matrix due to the increase of quartz in the mixture.     

An unusual type of unmixing in NaCl-KCl mixed crystals at room temperature

Water-catalysed decomposition of solid solutions of NaCl–KCl has been investigated at room temperature. The “wet” decomposition proceeds at abnormally high rate as compared to the usual “dry” decomposition. The formation and movement of the decomposition boundary is characteristic of the “wet” process. The influence of divalent impurities and partial decomposition of the usual type has been studied on the rate of the decomposition boundary movement. The mechanism of the unmixing is suggested which involves two interrelated process: the phase separation and formation of a system of interlocking microcracks acting as channels for the water transport from the surface into the bulk of the crystals. The open porosity resulting from the unmixing is confirmed experimentally.     

Characterization of the interface region in VPE GaAs

“Absolute” electron mobility values in the substrate interface region of n-type GaAs epitaxial layers were investigated. Space-charge scattering was found to be significant near the interface but could be minimized by the sequential growth of layers in one step. Our experimental results suggest that local deviations from stoichiometry may be responsible for the space-charge scattering.