An X-ray diffractometer for studying the effect of external fields on the structure and electron distribution of single crystals

1989 ◽  
Vol 22 (1) ◽  
pp. 42-45 ◽  
Author(s):  
L. A. Aslanov ◽  
V. A. Trunov ◽  
G. V. Fetisov ◽  
V. A. Priemyshev ◽  
V. B. Rybakov ◽  
...  
Keyword(s):  
Single Crystals ◽  
Structure Analysis ◽  
Equatorial Plane ◽  
Electron Distribution ◽  
Structural Changes ◽  
Horizontal Axis ◽  
The Other ◽  
External Fields ◽  
X Ray ◽  
Intensity Measurements

A new four-circle X-ray diffractometer (RMD) for single crystals is described that has only one (horizontal) axis of specimen rotation and a movable X-ray tube and detector. The diffractometer is characterized by the equatorial geometry. The equatorial plane rotates about the χ axis lying in this plane whereas the φ axis is fixed. This permits the use of various external (electromagnetic, magnetic etc.) fields applied to specimens along the φ axis. The angles between this direction and all the other crystallographic directions in the specimen remain constant in the course of intensity measurements. The designed RMD diffractometer allows the study of structural changes and electron distribution variations in a crystal subjected to external actions. The geometry and the design of the goniometer are considered in detail. Experiments carried out on the RMD diffractometer have demonstrated its efficiency for precision X-ray structure analysis.

X-Ray Diffractometry of Polymers by a Transmission Method

1964 ◽  
Vol 8 ◽  
pp. 151-161
Author(s):  
Zigmond W. Wilchinsky
Keyword(s):  
The Other ◽  
Reflection Method ◽  
Transmission Method ◽  
X Ray ◽  
Intensity Measurements ◽  
Other Hand ◽  
Line Asymmetry ◽  
Line Positions

AbstractThe practicability of using a symmetrical transmission method for accurate measurement of line positions and intensities for polymer samples was investigated. In comparison with the conventional symmetrical reflection method, the transmission method has some inherent advantages in the measurement of line positions. Very little extraneous line asymmetry is introduced by transmission, and errors due to sample misalignment can usually be corrected empirically. On the other hand, the reflection method introduces noticeable line asymmetry and a shift of the center of intensity toward smaller 2θ. Also, errors due to sample misalignment may be difficult to correct. Intensity measurements can usually be made with about the same accuracy by either method. However, the transmission method is less sensitive to misalignment errors, especially at the lower diffraction angles.

scholarly journals A Salt Metathesis Route To Ruthenium Carbene Complex Isomers With Pyridine Dicarboxamide-Derived Chelate Pincer Ligands

2007 ◽  
Vol 62 (6) ◽  
pp. 783-790 ◽  
Author(s):  
Carolin Wallenhorst ◽  
Kirill V. Axenov ◽  
Joseph S. M. Samec ◽  
Roland Fröhlich ◽  
Gerhard Erker
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Pincer Ligands ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbene Complex ◽  
Related Complex

Reaction of the doubly deprotonated pyridine 2,6-dicarboxamido ligand (1) with (PCy3)2Cl2 Ru=CHPh (3a) in THF gave a mixture of (lig)(PCy3)Ru=CHPh isomers (4). The pentane soluble N,N,O-4 isomer was isolated by extraction and characterized by X-ray diffraction. The O,N, O-4 isomer was identified in the residue. Single crystals of the closely related complex (lig)(NHC) Ru=CHPh, O,N,O-5, were obtained from the reaction of 1 with (NHC)(PCy3)Cl2Ru=CHPh (3b) and used for the X-ray crystal structure analysis of the system

Preparation of Carboranyl and Dodecaborate Derivatives of Coumarin

2007 ◽  
Vol 72 (12) ◽  
pp. 1740-1754 ◽  
Author(s):  
Eugen Justus ◽  
Dana T. Izteleuova ◽  
Alexander V. Kasantsev ◽  
Mendel M. Axartov ◽  
Enno Lork ◽  
...  
Keyword(s):  
Structure Analysis ◽  
The Other ◽  
Magnesium Salt ◽  
Ester Bond ◽  
Coumarin Derivatives ◽  
X Ray ◽  
Derivatives Of ◽  
Coumarin Ring

A series of derivatives of coumarin (2H-chromen-2-one) and 6,7-benzocoumarin (3H-benzo-[f]chromen-3-one) carrying the o-carborane, m-carborane, and dodecaborate clusters, has been obtained. X-ray structure analysis has been carried out for three of the products. The addition of o-carborane occurs in the 4-position of the coumarin ring, in a stereoselective way, independent of whether the cluster was reacted as the lithium or magnesium salt. m-Carborane gives two products, one being the result of 1,2-addition to an exocyclic ester bond and 1,4-addition to the coumarin system, the other resulting from 1,4-addition. The negatively charged dodecaborate derivatives obtained, link the cluster via oxygen or sulfur and an appropriate linker to a 7-hydroxy-substituted coumarin. For the coumarin derivatives, an o-carboranecarbonyl derivative could also be obtained.

scholarly journals Growing of Mercury-Indium Telluride Perfect Single Crystals

2016 ◽  
Vol 17 (1) ◽  
pp. 129-133
Author(s):  
O.V. Galochkin ◽  
Y.D. Zakharuk ◽  
V.M. Sklyarchuk ◽  
V.Z. Tsaliy ◽  
A.A. Asheulov ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Single Crystals ◽  
Structure Analysis ◽  
Zone Melting ◽  
X Ray ◽  
Modified Method ◽  
Indium Telluride

The perfect single crystals of mercury-indium telluride were grown by the modified method of zone melting. The differential thermal analysis (DTA) and X-ray structure analysis are performed.

scholarly journals Synthesis and Characterization of Cyclic Silenolates

2014 ◽  
Author(s):  
Michael Haas ◽  
Roland Fischer ◽  
Ana Torvisco ◽  
Harald Stueger
Keyword(s):  
Single Crystals ◽  
Structure Analysis ◽  
High Selectivity ◽  
Ring Cleavage ◽  
Synthesis And Characterization ◽  
Nmr Analysis ◽  
Subsequent Reaction ◽  
X Ray ◽  
Carbonyl Function

Based on earlier work by Ottosson [1] and Ohshita [2] the previously unknown cyclic silenolates 1a-c and 2a-b have been synthesized by the reaction of acylcyclohexasilanes with one or two equivalents of KOtBu. The nature of the anions (silenide or silenolate) and consequently the outcome of subsequent reaction steps largely depends on the substituent R at the carbonyl function. Detailed NMR-analysis of 1a-c and 2a-b corroborate this deduction. Furthermore, for 1a-c and 2a-b single crystals which were suitable for X-ray structure analysis could be grown. Very interesting is the reactivity of 1b, which at 50°C undergoes a hitherto unknown 1,4-trimethylsilyl-migration followed by a ring cleavage of the cyclohexasilane cycle to form the anion 3a. The high selectivity of these reactions is demonstrated by the formation of an acyl-functionalized bicyclo-2,2,2-octasilane in >90% yield from 2a and \(ClSiMe_{2}SiMe_{2}Cl\).

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.

Crystallographic studies on single crystals of doped and undoped Bi-Sr-Ca-Cu-O superconductors

1990 ◽  
Vol 48 (4) ◽  
pp. 78-79
Author(s):  
Brigitte H. Krause ◽  
Y. C. Chang ◽  
P. Z. Jiang ◽  
D. J. Lam
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
Layer Structure ◽  
The Other ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer Sequence ◽  
Tetragonal Unit Cell ◽  
Chemical Disorder

Diffraction data on single crystals of low Tc phase of Bi-Sr-Ca-Cu-O superconductor indicated a well developed layer structure, but with structural and chemical disorder within the layers. The lattice constant c and the layer sequence for the pseudo-tetragonal unit cell were determined from x-ray diffraction measurements of the 006 reflections. They were found to be 30.84(2) Å for the undoped compound and the same 30.84(2) Å for the lead doped crystals indicating the low superconducting transition temperature (Tc = 80 K) phase. The c-dimension for single crystals doped with both antimony and lead was 29.02(5) Å. Polycrystalline samples of that compound on the other hand formed the high temperature (Tc = 107 K) modification with c = 36.9(6) Å, determined from electron diffraction. A mixture of phases with different stacking of layers was indicated by splitting of diffraction spots. The direction of c was also less well defined in the lead-antimony doped single crystals than in the other two compounds.

Correction for Non-Linearity of Proportional Counter Systems in Electron Probe X-Ray Microanalysis

1965 ◽  
Vol 9 ◽  
pp. 208-220 ◽  
Author(s):  
Kurt F. J. Heinrich ◽  
Donald Vieth ◽  
Harvey Yakowitz
Keyword(s):  
Theoretical Basis ◽  
Electron Probe ◽  
Dead Time ◽  
Pulse Height ◽  
The Other ◽  
Time Effects ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Intensity Measurements

AbstractWhile the theoretical basis for the correction of non-linearity of detector systems is well known, methods for the determination of dead-time effects must be adapted to electron probe microanalyzer systems. Two such methods, one employing both X-ray and current measurements and the other employing simultaneous X-ray measurements on two spectrometers, are described. The effect of pulse-height shrinkage at high counting rates on the linearity of the detector system is discussed. When the proposed corrections for the dead-time of X-ray detector systems employing proportional counters are applied to the X-ray intensity measurements obtained with the electron probe microanalyzer, count rates as high as 50,000 counts/sec can be used.

scholarly journals The thermal expansion of bismuth by X-ray measurements

1934 ◽  
Vol 143 (849) ◽  
pp. 465-472 ◽  
Keyword(s):  
Thermal Expansion ◽  
Melting Point ◽  
Single Crystals ◽  
Room Temperature ◽  
The Other ◽  
Optical Methods ◽  
Lattice Expansion ◽  
X Ray ◽  
Expansion Curve ◽  
Methods Of Measurement

X-ray measurements recently carried out by the author on the lattice expansion of silver and quartz showed that the coefficients of thermal expansion, over the ranges investigated, are the same as those observed for the specimen as a whole using optical methods. Goetz and Hergenrother, on the other hand, from X-ray measurements on the coefficients of thermal expansion of single crystals of bismuth, claimed to have found a large difference between values obtained by the two methods of measurement. A possible explanatiion of this that their accuracy is not sufficient to establish definitely the deviation of the X-ray measurements from the optical expansion curve. The author has since made X-ray measurements on the expansion of the bismuth lattice from room temperature to just below the melting point, and finds no evidence of such a discrepancy as Goetz and Hergenrother record.

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