scholarly journals Determination of structural chirality of berlinite and quartz using resonant x-ray diffraction with circularly polarized x-rays

2010 ◽  
Vol 81 (14) ◽  
Author(s):  
Yoshikazu Tanaka ◽  
Taro Kojima ◽  
Yasutaka Takata ◽  
Ashish Chainani ◽  
Stephen W. Lovesey ◽  
...  
Keyword(s):  
X Rays ◽  
X Ray Diffraction ◽  
Circularly Polarized ◽  
X Ray

Erratum: Determination of structural chirality of berlinite and quartz using resonant x-ray diffraction with circularly polarized x-rays [Phys. Rev. B81, 144104 (2010)]

2011 ◽  
Vol 84 (21) ◽  
Author(s):  
Yoshikazu Tanaka ◽  
Taro Kojima ◽  
Yasutaka Takata ◽  
Ashish Chainani ◽  
Stephen W. Lovesey ◽  
...  
Keyword(s):  
X Rays ◽  
X Ray Diffraction ◽  
Circularly Polarized ◽  
X Ray

scholarly journals Electronic Excitations and Radiation Damage in Macromolecular Crystallography

Crystals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 273 ◽  
Author(s):  
José Brandão-Neto ◽  
Leonardo Bernasconi
Keyword(s):  
Chemical Information ◽  
X Rays ◽  
Electronic Excitations ◽  
Macromolecular Crystallography ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Successful Approach ◽  
Structural Research

Macromolecular crystallography at cryogenic temperatures has so far provided the majority of the experimental evidence that underpins the determination of the atomic structures of proteins and other biomolecular assemblies by means of single crystal X-ray diffraction experiments. One of the core limitations of the current methods is that crystal samples degrade as they are subject to X-rays, and two broad groups of effects are observed: global and specific damage. While the currently successful approach is to operate outside the range where global damage is observed, specific damage is not well understood and may lead to poor interpretation of the chemistry and biology of the system under study. In this work, we present a phenomenological model in which specific damage is understood as the result of a single process, the steady excitation of crystal electrons caused by X-ray absorption, which acts as a trigger for the bulk effects that manifest themselves in the form of global damage and obscure the interpretation of chemical information from XFEL and synchrotron structural research.

scholarly journals Electronic Excitations and Radiation Damage in Macromolecular Crystallography

2018 ◽  
Author(s):  
José Brandão-Neto ◽  
Leonardo Bernasconi
Keyword(s):  
Chemical Information ◽  
X Rays ◽  
Electronic Excitations ◽  
Macromolecular Crystallography ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Successful Approach ◽  
Structural Research

Macromolecular crystallography at cryogenic temperatures has so far provided the majority of the experimental evidence that underpins the determination of the atomic structures of proteins and other biomolecular assemblies by means of single crystal X-ray diffraction experiments. One of the core limitations of the current methods is that crystal samples degrade as they are subject to X-rays, and two broad groups of effects are observed: global and specific damage. While the currently successful approach is to operate outside the range where global damage is observed, specific damage is not well understood and may lead to poor interpretation of the chemistry and biology of the system under study. In this work, we present a phenomenological model in which specific damage is understood as the result of a single process, the steady excitation of crystal electrons caused by X-ray absorption, which acts as a trigger for the bulk effects that manifest themselves in the form of global damage and obscure the interpretation of chemical information from XFEL and synchrotron structural research.

The Measurement of Elastic Constants for the Determination of Stresses by X-Rays

1983 ◽  
Vol 27 ◽  
pp. 159-170 ◽  
Author(s):  
K. Perry ◽  
I.C. Noyan ◽  
P.J. Rudnik ◽  
J.B. Cohen
Keyword(s):  
Interplanar Spacing ◽  
Measuring System ◽  
Laboratory System ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Measured Change ◽  
Non Destructive ◽  
Applied Stresses

Residual and applied stresses (σij) are often measured via X-ray diffraction, by calculating the resultant elastic strains (ϵij) from the measured change in interplanar spacing (“d”). This method is non-destructive, reasonably reproducible (typically ±14 MPa), can be carried out in the field, and is readily automated to give values to an operator-specified precision , Let Li represent the axes of the measuring system with L3 normal to the diffracting planes, and Pi represent the sample axes. These axes are illustrated in Figure 1. In what follows, primed stresses and strains are in the laboratory system, while unprimed values are in the sample system.

scholarly journals Multiple scattering in grazing-incidence X-ray diffraction: impact on lattice-constant determination in thin films

2016 ◽  
Vol 23 (3) ◽  
pp. 729-734 ◽  
Author(s):  
Roland Resel ◽  
Markus Bainschab ◽  
Alexander Pichler ◽  
Theo Dingemans ◽  
Clemens Simbrunner ◽  
...  
Keyword(s):  
Thin Films ◽  
Critical Angle ◽  
Grazing Incidence ◽  
X Rays ◽  
Organic Thin Film ◽  
X Ray Diffraction ◽  
Reliable Determination ◽  
X Ray ◽  
Out Of Plane

Dynamical scattering effects are observed in grazing-incidence X-ray diffraction experiments using an organic thin film of 2,2′:6′,2′′-ternaphthalene grown on oxidized silicon as substrate. Here, a splitting of all Bragg peaks in the out-of-plane direction (z-direction) has been observed, the magnitude of which depends both on the incidence angle of the primary beam and the out-of-plane angle of the scattered beam. The incident angle was varied between 0.09° and 0.25° for synchrotron radiation of 10.5 keV. This study reveals comparable intensities of the split peaks with a maximum for incidence angles close to the critical angle of total external reflection of the substrate. This observation is rationalized by two different scattering pathways resulting in diffraction peaks at different positions at the detector. In order to minimize the splitting, the data suggest either using incident angles well below the critical angle of total reflection or angles well above, which sufficiently attenuates the contributions from the second scattering path. This study highlights that the refraction of X-rays in (organic) thin films has to be corrected accordingly to allow for the determination of peak positions with sufficient accuracy. Based thereon, a reliable determination of the lattice constants becomes feasible, which is required for crystallographic structure solutions from thin films.

Oxford HEXameter: Laboratory High Energy X-Ray Diffractometer for Bulk Residual Stress Analysis

2006 ◽  
Vol 524-525 ◽  
pp. 743-748 ◽  
Author(s):  
Alexander M. Korsunsky ◽  
Shu Yan Zhang ◽  
Daniele Dini ◽  
Willem J.J. Vorster ◽  
Jian Liu
Keyword(s):  
Accurate Determination ◽  
High Energy ◽  
Energy Dispersive ◽  
Detector Response ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Instrument ◽  
Synchrotron Beamlines

Diffraction of penetrating radiation such as neutrons or high energy X-rays provides a powerful non-destructive method for the evaluation of residual stresses in engineering components. In particular, strain scanning using synchrotron energy-dispersive X-ray diffraction has been shown to offer a fast and highly spatially resolving measurement technique. Synchrotron beamlines provide best available instruments in terms of flux and low beam divergence, and hence spatial and measurement resolution and data collection rate. However, despite the rapidly growing number of facilities becoming available in Europe and across the world, access to synchrotron beamlines for routine industrial and research use remains regulated, comparatively slow and expensive. A laboratory high energy X-ray diffractometer for bulk residual strain evaluation (HEXameter) has been developed and built at Oxford University. It uses a twin-detector setup first proposed by one of the authors in the energy dispersive X-ray diffraction mode and allows simultaneous determination of macroscopic and microscopic strains in two mutually orthogonal directions that lie approximately within the plane normal to the incident beam. A careful procedure for detector response calibration is used in order to facilitate accurate determination of lattice parameters by pattern refinement. The results of HEXameter measurements are compared with synchrotron X-ray data for several samples e.g. made from a titanium alloy and a particulate composite with an aluminium alloy matrix. Experimental results are found to be consistent with synchrotron measurements and strain resolution close to 2×10-4 is routinely achieved by the new instrument.

X-Ray Diffraction Determination of Texture and Stress in Damascene Fabricated Copper Interconnects

1999 ◽  
Vol 563 ◽  
Author(s):  
Delrose Winter ◽  
Paul R. Besser
Keyword(s):  
Incident Beam ◽  
Preferred Orientation ◽  
Copper Interconnects ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Determination ◽  
Lattice Planes ◽  
Excellent Tool

AbstractX-Ray diffraction (XRD) provides an excellent tool for the measurement of both stress and texture (preferred orientation) on fabricated damascene interconnect structures. Since x-ray diffraction provides a direct measurement of lattice spacings, film strain can be measured directly. Also, since the intensity of diffracted x-rays is proportional to the density of lattice planes oriented in diffracting condition with respect to the incident beam, both the direction and extent of preferred orientation can be accurately measured. Special techniques and considerations are necessary when examining damascene interconnect structures with XRD which are not necessary with blanket films. These techniques are discussed and described in order to aid in obtaining meaningful XRD data and a correct interpretation of the results.

scholarly journals Quantitative phase analysis by X-ray diffraction – Simple routes

2015 ◽  
Vol 34 (1) ◽  
pp. 33 ◽  
Author(s):  
Stanko Popović
Keyword(s):  
Phase Analysis ◽  
Great Difficulty ◽  
Quantitative Phase Analysis ◽  
Spectroscopic Techniques ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multiphase Material ◽  
Ideal Technique

<p>        The elemental composition of a multiphase material can be obtained by means of chemical and spectroscopic techniques. However, these techniques face a great difficulty in distinguishing the chemical identity of the phases present in the material and in derivation of the fractions of particular phases. X-ray powder diffraction seems to be an ideal technique for the analysis of a multiphase material. Each crystalline phase of the material gives its characteristic diffraction pattern independently of the other phases; this fact makes it possible to identify the phase of interest and to determine its fraction. The intensities of diffraction lines of a given phase are proportional to its fraction and an appropriate quantitative analysis can be performed after the application of the correction for the absorption of X-rays in the material.</p><p class="IUCrfigurecaption">        The principles of quantitative X-ray diffraction phase analysis of a multiphase material are presented, with a special attention paid to the doping methods. The following methods are described: (<em>i</em>) determination of the fraction of a phase using repeated dopings, (<em>ii</em>) determination of the fraction of a phase using a single doping, (<em>iii</em>) simultaneous determination of the fractions of several phases using a single doping; (<em>iv</em>) determination of the fraction of the dominant phase. The applicability of the doping methods is stated and the optimum conditions to minimize systematic errors are discussed. Recent approaches in quantitative X-ray diffraction phase analysis are also mentioned in short.</p>

The Interaction of Bio-Molecules with Lipid Membranes Studied by X-ray Diffraction

2014 ◽  
Vol 228 (10-12) ◽  
Author(s):  
Maikel Rheinstädter ◽  
Laura Toppozini ◽  
Hannah Dies
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Quantitative Information ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Molecular Ordering ◽  
Indispensable Tool

AbstractFor the past 100 years, X-ray diffraction has been a powerful and indispensable tool to study the structure of matter. The challenge when studying molecular ordering in biological materials is their inherent disorder and strong fluctuations, which often suppress the formation of Bragg peaks. In the case of membranes, X-rays can detect molecules inside and confined between membranes. In this article we review examples to highlight the capabilities and accomplishments of X-ray scattering for the determination of membrane structure. X-ray diffraction gives quantitative information about partitioning of a small molecule, ethanol, in lipid bilayers. By taking amyloid-

Twenty Years of Progress in X-Ray Diffraction Techniques

1961 ◽  
Vol 5 ◽  
pp. 1-12
Author(s):  
Andre Guinier
Keyword(s):  
Electron Microscopy ◽  
List Type ◽  
X Rays ◽  
Type Number ◽  
Rational Utilization ◽  
X Ray Diffraction ◽  
New Approach ◽  
X Ray ◽  
Near Future

AbstractAlthough no revolutionary advance has been achieved in the last two decades, X-ray diffraction is not to be considered as a quiescent field of physics. Actually many improvements, in theory as well as in experiment, slight by themselves but very numerous, have considerably increased the efficiency of techniques such as the determination of crystal structures, the analysis of crystalline phases, and the applications of X-rays to various problems of the physics of solids. Only the two last points will be dealt with here:1.Crystalline phase analysis. The development of a satisfactory atlas of powder patterns has been too slow, and the data are not yet complete and precise enough to permit a rational utilization of the modern diffractometers. A very interesting new approach is the systematic indexing of the powder patterns which would be possible with computers. In the near future, anyone should be able to analyze a powder at any temperature as an easy routine experiment.2.The study of lattice defects. X-ray techniques are now in competition with electron microscopy, the development of which has been very successful in recent years. Now we have a better understanding of the possibilities of both techniques. X-rays give better results to determine the statistics of an extended disorder even if it is slight (e.g., degrees of order in a solid solution), and the microscope is more powerful for the detection of large but rare defects (e.g., dislocations).

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