scholarly journals A mini-goniometer for X-ray diffraction studies down to 4 K on four-circle diffractometers equipped with two-dimensional detectors

2007 ◽  
Vol 40 (3) ◽  
pp. 526-531 ◽  
Author(s):  
Pierre Fertey ◽  
Roger Argoud ◽  
Pierre Bordet ◽  
Jacques Reymann ◽  
Cyril Palin ◽  
...  
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Mechanical Design ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Original Design ◽  
Data Set ◽  
X Ray ◽  
Density Analysis ◽  
Data Collections

A `universal' low-temperature device for laboratory X-ray diffractometers equipped with two-dimensional detectors has been developed. Single-crystal data collections can be performed down to 4 K. Owing to its original design, the completeness of the data set is not affected by the limited number of accessible orientations of the sample. Classical structure analysis can therefore be performed as well as high-resolution (high-angle) studies for electron-density analysis. Derived from an idea of Argoud & Muller [J. Appl. Cryst.(1989),22, 584–591], the sample is mounted on a holder magnetically coupled to the diffractometer φ axis. The coupling is achieved by mounting a master magnet in place of the usual goniometer head. This magnet drives a slave magnet fixed on the crystal holder: a two-axis mini-goniometer. This low-temperature arrangement is adaptable to any kappa-geometry single-crystal diffractometer equipped with a two-dimensional detector, and can be placed into various types of cryostat. This paper reports the home-made mechanical design and the performance of this device.

scholarly journals c-Perpendicular Orientation of Poly(ʟ-lactide) Films

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1572
Author(s):  
Baku Nagendra ◽  
Paola Rizzo ◽  
Christophe Daniel ◽  
Lucia Baldino ◽  
Gaetano Guerra
Keyword(s):  
Low Temperature ◽  
Film Plane ◽  
Wide Angle ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Amorphous Films ◽  
High Transparency ◽  
X Ray ◽  
Crystalline Forms ◽  
Induced Crystallization

Poly(ʟ-lactide) (PLLA) films, even of high thickness, exhibiting co-crystalline and crystalline α phases with their chain axes preferentially perpendicular to the film plane (c⊥ orientation) have been obtained. This c⊥ orientation, unprecedented for PLLA films, can be achieved by the crystallization of amorphous films as induced by low-temperature sorption of molecules being suitable as guests of PLLA co-crystalline forms, such as N,N-dimethylformamide, cyclopentanone or 1,3-dioxolane. This kind of orientation is shown and quantified by two-dimensional wide-angle X-ray diffraction (2D-WAXD) patterns, as taken with the X-ray beam parallel to the film plane (EDGE patterns), which present all the hk0 arcs centered on the meridian. PLLA α-form films, as obtained by low-temperature guest-induced crystallization, also exhibit high transparency, being not far from those of the starting amorphous films.

scholarly journals X-Ray Single Crystal Structural Analysis of Magnetically Oriented Microcrystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C1138-C1138
Author(s):  
Chiaki Tsuboi ◽  
Kazuki Aburaya ◽  
Shingo Higuchi ◽  
Fumiko Kimura ◽  
Masataka Maeyama ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Single Crystal ◽  
Three Dimensional ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Data Set ◽  
Uv Curable ◽  
X Ray

We have developed magnetically oriented microcrystal array (MOMA) technique that enables single crystal X-ray diffraction analyses from microcrystalline powder. In this method, microcrystals suspended in a UV-curable monomer matrix are there-dimensionally aligned by special rotating magnetic field, followed by consolidation of the matrix by photopolymerization. From thus achieved MOMAs, we have been succeeded in crystal structure analysis for some substances [1, 2]. Though MOMA method is an effective technique, it has some problems as follows: in a MOMA, the alignment is deteriorated during the consolidation process. In addition, the sample microcrystals cannot be recovered from a MOMA. To overcome these problems, we performed an in-situ X-ray diffraction measurement using a three-dimensional magnetically oriented microcrystal suspension (3D MOMS) of L-alanine. An experimental setting of the in-situ X-ray measurement of MOMS is schematically shown in the figure. L-alanine microcrystal suspension was poured into a glass capillary and placed on the rotating unit equipped with a pair of neodymium magnets. Rotating X-ray chopper with 10°-slits was placed between the collimator and the suspension. By using this chopper, it was possible to expose the X-ray only when the rotating MOMS makes a specific direction with respect to the impinging X-ray. This has the same effect as the omega oscillation in conventional single crystal measurement. A total of 22 XRD images of 10° increments from 0° to 220° were obtained. The data set was processed by using conventional software to obtain three-dimensional molecular structure of L-alanine. The structure is in good agreement with that reported for the single crystal. R1 and wR2 were 6.53 and 17.4 %, respectively. RMSD value between the determined molecular structure and the reported one was 0.0045 Å. From this result, we conclude that this method can be effective and practical to be used widely for crystal structure analyses.

Synthesis, Structure and Properties of Two-Dimensional Coordination Polymer Based on 3,5-di(benzimidazol-1-yl)pyridine

2020 ◽  
Vol 42 (2) ◽  
pp. 249-249
Author(s):  
Guo Jun Wu Guo Jun Wu
Keyword(s):  
Infrared Spectroscopy ◽  
Coordination Polymer ◽  
Single Crystal ◽  
Photocatalytic Degradation ◽  
Elemental Analysis ◽  
Solvothermal Reaction ◽  
Two Dimensional ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
X Ray

[Cu(L)(AIP)·1.5H2O]n (1) [L= 3,5-di(benzimidazol-1-yl)pyridine, H2AIP= 5-aminoisophthalic acid] was prepared by the solvothermal reaction, which was characterized by single-crystal X–ray diffraction, infrared spectroscopy, and elemental analysis. 1 exhibits an infinite two dimensional [Cu(AIP)]n sheet parallel to (0 1 1) crystal plane. Furthermore, complex 1 displays good photocatalytic degradation of methyl blue (MB).

scholarly journals Removing multiple outliers and single-crystal artefacts from X-ray diffraction computed tomography data

2015 ◽  
Vol 48 (6) ◽  
pp. 1943-1955 ◽  
Author(s):  
Antonios Vamvakeros ◽  
Simon D. M. Jacques ◽  
Marco Di Michiel ◽  
Vesna Middelkoop ◽  
Christopher K. Egan ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Single Crystal ◽  
Tomographic Reconstruction ◽  
Projection Data ◽  
Data Sets ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Tomography Data

This paper reports a simple but effective filtering approach to deal with single-crystal artefacts in X-ray diffraction computed tomography (XRD-CT). In XRD-CT, large crystallites can produce spots on top of the powder diffraction rings, which, after azimuthal integration and tomographic reconstruction, lead to line/streak artefacts in the tomograms. In the simple approach presented here, the polar transform is taken of collected two-dimensional diffraction patterns followed by directional median/mean filtering prior to integration. Reconstruction of one-dimensional diffraction projection data sets treated in such a way leads to a very significant improvement in reconstructed image quality for systems that exhibit powder spottiness arising from large crystallites. This approach is not computationally heavy which is an important consideration with big data sets such as is the case with XRD-CT. The method should have application to two-dimensional X-ray diffraction data in general where such spottiness arises.

scholarly journals Further errors in polymorph identification: furosemide and finasteride

2006 ◽  
Vol 62 (4) ◽  
pp. 689-691 ◽  
Author(s):  
Sohrab Karami ◽  
Yang Li ◽  
David S. Hughes ◽  
Michael B. Hursthouse ◽  
Andrea E. Russell ◽  
...  
Keyword(s):  
Single Crystal ◽  
Incomplete Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Data Collections ◽  
Mistaken Identification

Reassessment of the reported single-crystal X-ray diffraction characterization of polymorphs of furosemide and finasteride shows that, in each case, incomplete data collections have resulted in the mistaken identification of two forms that are, in fact, identical.

The Great Barrier Reef Expedition 1928–29: The crystal structure and occurrence of weddellite, ideally CaC2O4·2.5H2O, from the Low Isles, Queensland

2016 ◽  
Vol 80 (2) ◽  
pp. 399-406 ◽  
Author(s):  
Stuart J. Mills ◽  
Andrew G. Christy
Keyword(s):  
Crystal Structure ◽  
Coral Reef ◽  
Low Temperature ◽  
Great Barrier Reef ◽  
Single Crystal ◽  
Structure Study ◽  
Barrier Reef ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Report

Abstract“Envelope crystals” collected during The Great Barrier Reef Expedition in May 1929 have been studied using low-temperature synchrotron single-crystal X-ray diffraction. The crystals are shown to be weddellite, with the largest content of zeolitic water reported to date. A new H2O site has been located within the crystal structure. Study of the crystals show that the end-member formula for weddellite should be reported as CaC2O4·(2.5 – x)H2O, where 0≤x≤ 0.25, instead of CaC2O4·(2H2O or CaC2O4·(2 + x )H2O. This is also the first report of weddellite occurring in a coral reef.

A system for doing low temperature-high pressure single crystal X-ray diffraction with a synchrotron source

1991 ◽  
Vol 6 (6) ◽  
pp. 379-388 ◽  
Author(s):  
R. LeToullec ◽  
P. Loubeyre ◽  
J. P. Pinceaux ◽  
H. K. Mao ◽  
J. Hu
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray
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