Search results for "Stack"
showing 10 items of 392 documents
Low-Q peak in X-ray patterns of choline-phenylalanine and homophenylalanine: a combined effect of chain and stacking
2016
Abstract In this contribution we report for the first time the X-ray patterns of choline-phenylalanine and choline-homophenylalanine ionic liquids. The presence of a low Q peak in both systems is another evidence that a long alkyl chain is not always needed to establish a nanodomain segregation in the liquid sufficient to be revealed by the diffraction experiment. These new data are compared with the diffraction patterns and the theoretical calculations of other choline-aminoacid ionic liquids recently reported. A significant role might be played by the stacking interactions between aromatic rings.
Structural characterization of Nigerian coals by X-ray diffraction, Raman and FTIR spectroscopy
2010
Abstract The structural parameters of six Nigerian coals were determined by X-ray diffraction, Raman and FTIR spectroscopy. This study reveals that the coals contain crystalline carbon of turbostratic structure with some amount of highly disordered amorphous carbon. The average lateral sizes ( L a ), stacking heights ( L c ) and interlayer spacing ( d 002 ) of the crystallite structures calculated from the X-ray intensities range from 16.47 to 25.70, 8.12 to 13.25 and 3.48 to 3.58 A, respectively. The L a values derived from the Raman spectra analyses using the classical linear relationship between 1/ L a and the D/G band ratio are higher (27.53–34.67 A) than values obtained from X-ray diff…
Columnar supramolecular architecture of crystals of 2-(4-Iodophenyl)-1,10-phenanthroline derived from values of intermolecular interaction energy
2011
Using results of X-ray diffraction study supramolecular architecture of crystals of 2-(4-iodophenyl)-1,10-phenanthroline has been analyzed on the basis of quantum-chemical calculations of intermolecular interactions energy. It is demonstrated that these crystals have three levels of organization. Molecules form stacked dimers with the highest binding energy (first level). These dimers represent basic unit of infinite columns stabilized by stacking interactions between dimers (second level). The energy of intermolecular interactions between neighbouring stacked columns is very close. This does not allow to figure out any layers in the crystal. Therefore crystals of this compound have columna…
Crossing the boundary between face-centred cubic and hexagonal close packed: the structure of nanosized cobalt is unraveled by a model accounting for…
2014
The properties of nanostructured cobalt in the fields of magnetic, catalytic and biomaterials depend critically on Co close packing. This paper reports a structural analysis of nanosized cobalt based on the whole X-ray diffraction (XRD) pattern simulation allowed by the Debye equation. The underlying structural model involves statistical sequences of cobalt layers and produces simulated XRD powder patterns bearing the concurrent signatures of hexagonal and cubic close packing (h.c.p. and f.c.c.). Shape, size distribution and distance distribution between pairs of atoms are also modelled. The simulation algorithm allows straightforward fitting to experimental data and hence the quantitative …
Crystal structure of disordered nanocrystalline $\alpha^{II}$-quinacridone determined by electron diffraction
2016
CrystEngComm 18(4), 529 - 535(2016). doi:10.1039/C5CE01855B
New zeolite-like RUB-5 and its related hydrous layer silicate RUB-6 structurally characterized by electron microscopy.
2020
RUB-5 and its related hydrous layer silicate RUB-6 were synthesized in the 1990s, but so far their structures have remained unknown due to their low crystallinity and disorder. The combination of 3D electron diffraction, X-ray powder diffraction, high-resolution transmission electron microscopy, structural modelling and diffraction simulations has enabled a comprehensive description of these two nanomaterials, revealng a new framework topology and a unique silica polymorph.
CADEM: calculate X-ray diffraction of epitaxial multilayers
2017
This article presents a powerful yet simple program, based on the general one-dimensional kinematic X-ray diffraction (XRD) theory, which calculates the XRD patterns of tailor-made multilayers and thus enables quantitative comparison of measured and calculated XRD data. As the multilayers are constructed layer by layer, the final material stack can be entirely arbitrary.
Investigation of Silicon Carbide Polytypes by Raman Spectroscopy
2014
Abstract Polytypes of colourless and coloured single crystals of silicon carbide (SiC) grown on SiC substrates by chemical vapour deposition are studied using Raman spectroscopy supplemented by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The SEM analysis of the defect stacking faults, inclusions of defects and their distribution has shown that they correlate with the peak positions of the obtained Raman spectra and with the XRD data on the crystal structure
STACKING-FAULTS IN VERY FINE PALLADIUM PARTICLES SUPPORTED ON PUMICE
1990
By means of an X-ray diffraction study, carried out with best-fitting procedures, of the asymmetry and peak maximum shifts of some reflections, stacking-faults in the FCC lattice of very fine palladium particles supported on pumice were detected using the Warren-Wagner-Cohen theoretical approach.
Triphenylmethyl and triphenylsilyl based molecular glasses for photonic applications
2015
Triphenylmethyl and triphenylsilyl structural fragments can be used to obtain glass forming, solution processable materials from polar chromophore molecules. Large number of compounds has been synthesized taking advantage of this approach, making it possible to identify some structure-property relations. Regarding the non-linear optical (NLO) properties of the given materials it is evident that triphenylmethyl groups help shielding unwanted NLO efficiency limiting dipolar interactions between polar chromophores in solid films. Chromophore stacking is still observed for compounds with large dipole momentum values. The glass transition temperatures of the compounds increase with the molecular…