scholarly journals On the interpretation of X-ray, single crystal, rotation photographs

1926 ◽  
Vol 113 (763) ◽  
pp. 117-160 ◽  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
The Other ◽  
X Rays ◽  
X Ray ◽  
Powder Method ◽  
Convenient Form ◽  
Other Hand ◽  
Rotation Method ◽  
Laue Method

In the development of the study of crystals by X-rays the methods used divide themselves naturally into four types : the Bragg Ionisation Spectrometer method, the Laue method, the Powder method of Debye and Scherrer, and the Rotating Crystal method of Rinne, Schiebold and Polyani. The techniques of the first three of these methods are fully explained in such books as ‘ X-Rays and Crystal Structure,’ by W. H. and W. L. Bragg, ‘ The Structure of Crystals,’ by Wyckoff, and ‘ Krystalle und Rontgenstrahlen,’ by Ewald, as well as in original papers. On the other hand, the rotation method is only slightly touched on in these works, the literature is scattered in a great number of papers, and the technique has not so far been described at any length in a convenient form. Particularly in English, references to it are scanty. In this paper the author has tried to give a concise account of the method, together with various types of charts and tables as it is used in the Davy Faraday Laboratory. The methods described differ in certain respects from those used on the Continent,* but they have been found to be rapid and sufficiently accurate.

Molecular tapes in the structure of isoguaninium chloride

2017 ◽  
Vol 74 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Urszula Anna Budniak ◽  
Paulina Maria Dominiak
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Charge Density ◽  
Interaction Energy ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Structure

Isoguanine, an analogue of guanine, is of intrinsic interest as a noncanonical nucleobase. The crystal structure of isoguaninium chloride (systematic name: 6-amino-2-oxo-1H,7H-purin-3-ium chloride), C5H6N5O+·Cl−, has been determined by single-crystal X-ray diffraction. Structure analysis was supported by electrostatic interaction energy (E es) calculations based on charge density reconstructed with the UBDB databank. In the structure, two kinds of molecular tapes are observed, one parallel to (010) and the other parallel to (50\overline{4}). The tapes are formed by dimers of isoguaninium cations interacting with chloride anions. E es analysis indicates that cations in one kind of tape are oriented so as to minimize repulsive electrostatic interactions.

Crystal Structure of Calcium Picrate Pentahydrate: A New Eight-Coordinate Stereochemistry for [M(bidentate)2(unidentate)4]

1979 ◽  
Vol 32 (2) ◽  
pp. 301 ◽  
Author(s):  
V Diakiw ◽  
TW Hambley ◽  
DL Kepert ◽  
CL Raston ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Single Crystal ◽  
Title Compound ◽  
Lattice Site ◽  
The Other ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Triangular Face ◽  
X Ray

The crystal structure of the title compound, Ca(C6H2N307)2,5H2O, has been determined by single-crystal X-ray diffraction at 295(1) K and refined by least squares to a residual of 0.049 for 1513 'observed' reflections. Crystals are orthorhombic, Pmab, a 24.169(6), b l0.292(7), c 8.554(2) �, Z 4. The stereochemistry about the calcium has not been observed previously for the system [M(bidentate)2- (unidentate)4]; in the present structure, the calcium is coordinated by a pair of bidentate picrate ligands and the four water molecules in an array in which three of the water molecules occupy a triangular face of a square antiprism, the overall array having m symmetry. The remaining water molecule occupies a lattice site with no close interaction with the other species.

Synthesis and Structure of and Cation Distribution in the Zirconium Cluster Rb[(Zr6C)Cl15]

2008 ◽  
Vol 63 (5) ◽  
pp. 507-512 ◽  
Author(s):  
Henning W. Rohm ◽  
Martin Köckerling
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Cation Distribution ◽  
Type Structure ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coulombic Interactions ◽  
Cluster Network ◽  
Zirconium Cluster

Rb[(Zr6C)Cl15] was prepared by heating ZrCl4, Zr powder, RbCl and Al4C3 at 850 °C for 21 days. The crystal structure was determined by single crystal X-ray diffraction (space group Pmma, a = 18.484(3), b = 18.962(2), c = 9.708(1) Å, V = 2505.4(6) Å3, and Z = 4). Rb[(Zr6C)Cl15] crystallises in the Cs[Nb6Cl15]-type structure. It is built up from two interconnected types of cluster chains, one with linear Zr−Cla−a-Zr bridges, the other one with bent bridges. The rubidium cations are spread over three different sites within the cluster network which differs significantly from the cation distribution in the comparable potassium and caesium phases. The cation distribution can be rationalised considering the size of the cavities and the Coulombic interactions.

scholarly journals Die Kristallstruktur des Cyano-Elpasoliths [N(CH3)4]2CsFe(CN)6 / The Crystal Structure of the Cyano Elpasolite [N(CH3)4]2CsFe(CN)6

1982 ◽  
Vol 37 (12) ◽  
pp. 1534-1539 ◽  
Author(s):  
D. Babel
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
The Other ◽  
Methyl Groups ◽  
Orientational Disorder ◽  
Space Group ◽  
X Ray ◽  
Ray Methods ◽  
The Ideal

The crystal structure of the cubic compound [N(CH3)4]2CsFe(CN)6 was determined by X-ray methods: a = 2527.4(6) pm, space group Fd3c, Z = 32, Rg = 0.028 (260 independent single crystal reflections). The resulting distances within the practically undistorted Fe (CN)63- - octahedron are Fe-C = 193.4(6) and C-N = 115.7(7) pm. Compared to the ideal elpasolite structure of space group Fm3m, Z = 4, the octahedra are rotated by 7.4° through their 3 axis. This is discussed as caused by steric requirements of the tetramethylammonium groups (N-C = 148.4(10) and 149.1(38) pm, resp.). Three quarters of them, of which also the hydrogen positions could be located, are well oriented. The remaining quarter shows orientational disorder to approach similar contact distances as the other N(CH3)4+ ion exhibits between the methyl groups and the nitrogen ends of the anions

The perchlorotriphenylmethyl (PTM) radical

2013 ◽  
Vol 69 (3) ◽  
pp. 255-257 ◽  
Author(s):  
Judith Guasch ◽  
Xavier Fontrodona ◽  
Imma Ratera ◽  
Concepció Rovira ◽  
Jaume Veciana
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
The Other ◽  
X Ray Diffraction ◽  
Monoclinic Symmetry ◽  
Steric Strain ◽  
High Chemical ◽  
X Ray ◽  
Cl Atoms

In spite of the considerable understanding and development of perchlorotriphenylmethyl (PTM) radical derivatives, the preparation of crystals of the pure unsubstituted PTM radical, C19Cl15, suitable for single-crystal X-ray diffraction has remained a challenge since its discovery, and only two studies dealing with the crystal structure of the unsubstituted PTM radical have been published. In one study, the radical forms clathrates with aromatic solvents [Veciana, Carilla, Miravitlles & Molins (1987).J. Chem. Soc. Chem. Commun.pp. 812–814], and in the other the structure was determinedab initiofrom powder X-ray diffraction data [Rius, Miravitlles, Molins, Crespo & Veciana (1990).Mol. Cryst. Liq. Cryst.187, 155–163]. We report here the preparation of PTM crystals for single-crystal X-ray diffraction and their resolution. The structure, which shows monoclinic symmetry (C2/c), revealed a nonsymmetric molecular propeller conformation (D3symmetry) caused by the steric strain between theortho-Cl atoms, which protect the central C atom (sp2-hybridization and major spin density) and give high chemical and thermal persistence to the PTM. The supramolecular structure of PTM shows short Cl...Cl intermolecular interactions and can be described in terms of layers formed by rows of molecules positioned in a head-to-tail manner along thecaxis.

A Re-investigation of the Crystal Structure of the Perovskite PbZrO3 by X-ray and Neutron Diffraction

1997 ◽  
Vol 53 (1) ◽  
pp. 135-142 ◽  
Author(s):  
D. L. Corker ◽  
A. M. Glazer ◽  
J. Dec ◽  
K. Roleder ◽  
R. W. Whatmore
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Lead Zirconate ◽  
Conclusive Evidence ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Investigations

The crystal structure of the perovskite lead zirconate PbZrO3 has been redetermined using single-crystal X-ray diffraction (Mo Kα radiation, λ = 0.71069 Å). Single-crystal data at 100 K: space group. Pbam, a = 5.884 (1), b = 11.787 (3), c = 8.231 (2) Å, V = 570.85 Å3 with Z = 8, μ = 612.6 cm−1, D x = 8.06 Mg m−3, F(000) = 1168, final R = 0.033, wR = 0.061 over 555 reflections with I > 2σ(I). An investigation is made into previous contradicting reports of a possible disorder in the O atoms and their origin by examining the crystal pseudo-symmetry. Information distinguishing an ordered and disordered oxygen substructure is shown to reside in weak l odd reflections. Because of their extremely low intensities these reflections have not contributed sufficiently in previous X-ray structure investigations and hence, to date, conclusive evidence differentiating between ordered and disordered models has not been possible. By collecting single-crystal X-ray data at low temperature and by using exceptionally long scans on selected hkl, l odd, reflections, a new accurate structure determination is presented and discussed, showing the true ordered oxygen positions. Because of the large difference in scattering factors between lead and oxygen when using X-rays, a neutron diffraction Rietveld refinement using polycrystalline samples (D1A instrument, ILL, λ = 1.90788 Å) is also reported as further evidence to support the true ordered oxygen structure revealed by the low-temperature X-ray analysis.

scholarly journals Success or Failure of Chiral Crystallization of Similar Heterocyclic Compounds

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5691
Author(s):  
Cyprian M. Chunkang ◽  
Iris E. Ikome ◽  
Emmanuel N. Nfor ◽  
Yuta Mitani ◽  
Natsuki Katsuumi ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Single Crystal ◽  
Single Crystals ◽  
Heterocyclic Compounds ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
The Other ◽  
X Ray ◽  
Other Hand

Single crystals of two achiral and planar heterocyclic compounds, C9H8H3O(CA1) and C8H5NO2 (CA4), recrystallized from ethanol, were characterized by single crystal X-ray analysis, respectively, and chiral crystallization was observed only for CA1 as P212121 (# 19), whereas it was not observed for CA4 P21/c (# 14). In CA1, as a monohydrate, the hydrogen bonds were pronounced around the water of crystallization (O4), and the planar cyclic sites were arranged in parallel to slightly tilted positions. On the other hand, an anhydride CA4 formed a dimer by hydrogen bonds between adjacent molecules in the crystal, which were aggregated by van der Waals forces and placed in parallel planar cyclic sites.

Rotating crystal X-Ray photographs

1927 ◽  
Vol 21 (117) ◽  
pp. 258-271 ◽  
Author(s):  
Gilbert Greenwood
Keyword(s):  
Flat Plate ◽  
Ionization Chamber ◽  
The Other ◽  
X Rays ◽  
X Ray ◽  
Chamber Method ◽  
Powder Method ◽  
Small Crystal ◽  
Royal Institution

Since the original experiments of M. von Laue on the diffraction of X-rays by crystals, other and more suitable methods of research have been devised. The Bragg ionization-chamber method and the Debye-Scherrer powder method are now quite well known. The newest technique is that of the so-called 'rotating crystal', which is based essentially on some experiments of M. de Broglie. This method was first employed and developed in the Kaiser Wilhehm Institut für Faserstoffchemie in Berlin. It has recently been extended by the work of J. D. Bernal in the Royal Institution in London.There are two methods of making this type of photograph. In both a small crystal is rotated in a beam of X-rays and the reflected beams recorded photographically, in one case on a flat plate, and in the other on a cylindrical film the axis of which coincides with the axis about which the crystal is rotated.

THE HYPOPHYSIAL CONTROL OF THE X-RAY STERILIZED OVARY

1958 ◽  
Vol 17 (1) ◽  
pp. 1-12 ◽  
Author(s):  
D. L. INGRAM ◽  
ANITA M. MANDL
Keyword(s):  
Stromal Cells ◽  
The Other ◽  
Vaginal Smear ◽  
X Rays ◽  
Adult Rats ◽  
X Ray ◽  
Uterine Involution ◽  
Other Hand ◽  
X Irradiation

SUMMARY Adult rats which had been previously sterilized by means of X-rays were hypophysectomized a fortnight after the onset of continuous vaginal cornification (which begins within 40 days of X-irradiation [Mandl & Zuckerman, 1956]). The animals, including non-irradiated hypophysectomized controls, were killed at periods of 5–70 days after hypophysectomy. Cornified cells disappeared from the vaginal smear of non-irradiated rats within 3, and of irradiated rats within 4 days after hypophysectomy. The ovaries involuted rapidly in both groups of animals. Stromal cells decreased in size and post-hypophysectomy 'deficiency cells' appeared. On the other hand, the rate of uterine involution was slower in the X-irradiated animals after hypophysectomy than in the non-irradiated hypophysectomized controls. This finding indicates that in the absence of the pituitary, the X-irradiated ovary can produce more oestrogen than a non-irradiated ovary, or that the oestrogen it produces is biologically more active. After treatment with gonadotrophin, the 'deficiency cells' in the ovaries of both groups of animals disappeared. The X-irradiated hypophysectomized animals responded to the gonadotrophin less vigorously (as judged by an increase in ovarian and uterine size) than did the hypophysectomized controls.

Strong 5f Ferromagnetism in UH3-Based Materials

MRS Advances ◽  
2016 ◽  
Vol 1 (44) ◽  
pp. 2987-2992 ◽  
Author(s):  
Ladislav Havela ◽  
Mykhaylo Paukov ◽  
Ilya Tkach ◽  
Volodymyr Buturlim ◽  
Zdenek Matej ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Distribution Function ◽  
Curie Temperature ◽  
Pair Distribution Function ◽  
High Energy ◽  
The Other ◽  
X Rays ◽  
Other Hand ◽  
Pdf Analysis

ABSTRACT Several diverse types of UH3-based hydrides can be prepared by hydrogenation of bcc U-based alloys. Pair Distribution Function (PDF) analysis using high-energy X-rays identified that the (UH3)1-x Mo x hydrides are nanocrystalline, with the structure motif based mainly on the β-UH3 structure. α-UH3 represents a minority component. On the other hand, PDF of the (UH3)1-x Zr x hydrides corresponds well to the α-UH3 crystal structure. All the hydrides are ferromagnetic, with the Curie temperature T C reaching up to 203 K.

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