X-ray analysis of the crystal-structure of rutile and cassiterite

The present paper deals with the results obtained in the investigation of the atomic structure of rutile and cassiterite by the X-ray spectrometer. A detailed account of the method has been given by Prof. Bragg and his son, W. L. Bragg, in a series of papers communicated to the Royal Society. It consists essentially in allowing a narrow beam of monochromatic X-rays—in this case the rhodium rays—to fall on the face of the crystals, mounted on a spectrometer table, the axis of rotation of which passes through the face of the crystal. The beam is “reflected” by the atom planes parallel to this face, and thence passes into an ionisation chamber, containing methyl bromide in order to increase the ionisation current. The setting of crystal and chamber with regard to the incident beam corresponds to that for which ordinary light is reflected.

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The analysis of crystals by the X-ray spectrometer

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1914.0015 ◽

1914 ◽

Vol 89 (613) ◽

pp. 468-489 ◽

Cited By ~ 143

Keyword(s):

Royal Society ◽

Photographic Plate ◽

Exact Nature ◽

Photographic Method ◽

X Rays ◽

Alkaline Metal ◽

Powerful Method ◽

Narrow Beam ◽

X Ray Diffraction ◽

X Ray

In a former communication to the Royal Society, an attempt was made to determine for certain crystals the exact nature of the diffracting system which produces the Laue X-ray diffraction photographs. The crystals chosen for particular investigation were the isomorphous alkaline halides NaCl, KCl, KBr, and KI. As in the original experiments of Laue and his collaborators, a thin section of crystal was placed in the path of a narrow beam of X-rays, and the radiation diffracted by the crystal made its impression on a photographic plate. By noticing what differences were caused in the photograph by the substitution of heavier for lighter atoms in the crystal, a definite arrangement was decided on as that of the diffracting points of the crystalline grating. Though it was found possible in the case of these simple salts to determine the position of the atoms of alkaline metal and halogen, which constitute the elements of the dimensional diffraction grating, yet this method, which may be called the photographic method, is very limited in its range of applications. It was only the extremely simple nature of the NaCI structure which made its analysis possible. On the other hand, the X-ray spectrometer, which has been devised by W. H. Bragg for the purpose of studying the reflection of X-rays by crystals, affords a very much more powerful method of research into the structure of the crystal.

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Some Developments in the X-ray Analysis of Single-Crystals

Mathematical Proceedings of the Cambridge Philosophical Society ◽

10.1017/s0305004100011701 ◽

1927 ◽

Vol 23 (5) ◽

pp. 561-577

Author(s):

R. L. Aston

Keyword(s):

Single Crystal ◽

Single Crystals ◽

Incident Beam ◽

X Rays ◽

Surface Layers ◽

X Ray ◽

Axis Of Rotation ◽

Component Wave

A method has been devised by Dr Alex Müller for determining the orientation of a single-crystal of metal by photographic measurement of the reflection of characteristic X-rays from surface layers. The incident beam passes perpendicularly through an axis of rotation around which the crystal is turned until a reflection is obtained with one of the component wave-lengths of the X-rays.

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Is there a non-channeling orientation?

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100175193 ◽

1990 ◽

Vol 48 (4) ◽

pp. 412-413

Author(s):

J. A. Eades ◽

K. K. Christenson ◽

M. L. Andreessen

Keyword(s):

Crystal Structure ◽

Electron Flux ◽

Standard Form ◽

Incident Beam ◽

Unit Cell ◽

X Rays ◽

Host Crystal ◽

X Ray ◽

Incident Electron Beam ◽

Channeling Effect

In the standard form of ALCHEMI, the aim is to calculate the fraction of an impurity that is substitutional on each different sublattice of the host crystal. The result is calculated from the ratios of the of the intensities of the x rays emitted by the elements present. The ratios vary as a function of the angle of the incident electron beam because of electron channeling in the crystal structure. The channeling has the effect of making the electron density different in different parts of the unit cell. If the x-ray yield of one element goes up, the electron yield of any other element on the same sites (i.e. the same sublattice) in the crystal structure will go up in the same proportion. This variation can be used to calculate the fraction on each site.The calculation requires the measurement of the x-ray ratios at at least one angle with a strong channeling effect but also requires the measurement of the ratios at a condition of the incident beam that is “nonchanneling”, that is when the electron flux is uniform across the unit cell.

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X-ray crystal structure of a malonate-semialdehyde dehydrogenase fromPseudomonassp. strain AAC

Acta Crystallographica Section F Structural Biology Communications ◽

10.1107/s2053230x16020008 ◽

2017 ◽

Vol 73 (1) ◽

pp. 24-28 ◽

Cited By ~ 1

Author(s):

Matthew Wilding ◽

Colin Scott ◽

Thomas S. Peat ◽

Janet Newman

Keyword(s):

Crystal Structure ◽

Search Model ◽

Molecular Replacement ◽

X Rays ◽

X Ray Diffraction ◽

Acetyl Coa ◽

Space Group ◽

X Ray ◽

Semialdehyde Dehydrogenase

The NAD-dependent malonate-semialdehyde dehydrogenase KES23460 fromPseudomonassp. strain AAC makes up half of a bicistronic operon responsible for β-alanine catabolism to produce acetyl-CoA. The KES23460 protein has been heterologously expressed, purified and used to generate crystals suitable for X-ray diffraction studies. The crystals belonged to space groupP212121and diffracted X-rays to beyond 3 Å resolution using the microfocus beamline of the Australian Synchrotron. The structure was solved using molecular replacement, with a monomer from PDB entry 4zz7 as the search model.

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Synchrotron Nano-Diffraction Study of Thermally Treated Asbestos Tremolite from Val d’Ala, Turin (Italy)

Minerals ◽

10.3390/min8080311 ◽

2018 ◽

Vol 8 (8) ◽

pp. 311 ◽

Cited By ~ 2

Author(s):

Carlotta Giacobbe ◽

Jonathan Wright ◽

Dario Di Giuseppe ◽

Alessandro Zoboli ◽

Mauro Zapparoli ◽

...

Keyword(s):

Crystal Structure ◽

Heat Treatment ◽

Risk Management ◽

Structure Analysis ◽

X Rays ◽

X Ray Diffraction ◽

X Ray ◽

Adverse Health Effects ◽

Nano Crystalline ◽

Original Fibre

Nowadays, due to the adverse health effects associated with exposure to asbestos, its removal and thermal inertization has become one of the most promising ways for reducing waste risk management. Despite all the advances in structure analysis of fibers and characterization, some problems still remain that are very hard to solve. One challenge is the structure analysis of natural micro- and nano-crystalline samples, which do not form crystals large enough for single-crystal X-ray diffraction (SC-XRD), and their analysis is often hampered by reflection overlap and the coexistence of multiple fibres linked together. In this paper, we have used nano-focused synchrotron X-rays to refine the crystal structure of a micrometric tremolite fibres from Val d’Ala, Turin (Italy) after various heat treatment. The structure of the original fibre and after heating to 800 °C show minor differences, while the fibre that was heated at 1000 °C is recrystallized into pyroxene phases and cristobalite.

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Collimating Montel mirror as part of a multi-crystal analyzer system for resonant inelastic X-ray scattering

Journal of Synchrotron Radiation ◽

10.1107/s1600577516007426 ◽

2016 ◽

Vol 23 (4) ◽

pp. 880-886 ◽

Cited By ~ 6

Author(s):

Jungho Kim ◽

Xianbo Shi ◽

Diego Casa ◽

Jun Qian ◽

XianRong Huang ◽

...

Keyword(s):

Energy Resolution ◽

Incident Beam ◽

X Rays ◽

X Ray ◽

X Ray Scattering ◽

Angular Acceptance ◽

Crystal Analyzer ◽

Present Design ◽

Photon Source ◽

Ray Scattering

Advances in resonant inelastic X-ray scattering (RIXS) have come in lockstep with improvements in energy resolution. Currently, the best energy resolution at the IrL3-edge stands at ∼25 meV, which is achieved using a diced Si(844) spherical crystal analyzer. However, spherical analyzers are limited by their intrinsic reflection width. A novel analyzer system using multiple flat crystals provides a promising way to overcome this limitation. For the present design, an energy resolution at or below 10 meV was selected. Recognizing that the angular acceptance of flat crystals is severely limited, a collimating element is essential to achieve the necessary solid-angle acceptance. For this purpose, a laterally graded, parabolic, multilayer Montel mirror was designed for use at the IrL3-absorption edge. It provides an acceptance larger than 10 mrad, collimating the reflected X-ray beam to smaller than 100 µrad, in both vertical and horizontal directions. The performance of this mirror was studied at beamline 27-ID at the Advanced Photon Source. X-rays from a diamond (111) monochromator illuminated a scattering source of diameter 5 µm, generating an incident beam on the mirror with a well determined divergence of 40 mrad. A flat Si(111) crystal after the mirror served as the divergence analyzer. From X-ray measurements, ray-tracing simulations and optical metrology results, it was established that the Montel mirror satisfied the specifications of angular acceptance and collimation quality necessary for a high-resolution RIXS multi-crystal analyzer system.

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Micro-X-Ray Fluorescence Analysis on a Synchrotron Radiation Wiggler Beam Line

Advances in X-ray Analysis ◽

10.1154/s0376030800013227 ◽

1991 ◽

Vol 35 (B) ◽

pp. 995-1000

Author(s):

J.V. Gilfrich ◽

E.F. Skelton ◽

S.B. Qadri ◽

N.E. Moulton ◽

D.J. Nagel ◽

...

Keyword(s):

Synchrotron Radiation ◽

National Laboratory ◽

Incident Beam ◽

Fluorescence Analysis ◽

High Energy ◽

Brookhaven National Laboratory ◽

Beam Line ◽

X Rays ◽

X Ray ◽

Electron Orbit

AbstractIt has been well established over recent years that synchrotron radiation possesses some unique features as a source of primary x-rays for x-ray fluorescence analysis. Advantage has been taken of the high intensity emanating from the bending magnets of storage rings to develop x-ray microprobes utilizing apertures or focussing optics, or both, to provide a beam spot at the specimen of the order of micrometers. The use of insertion devices wigglers and undulatora, can further increase the available intensity, especially for the high energy photons. Beam Line X-17C at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory, accepts the unmodified continuum radiation from a superconducting wiggler in the storage ring. Some initial XRF measurements have been made on this beam line using apertures in the 10 to 100 micrometer range. The fluorescent radiation was measured by an intrinsic Ge detector having an energy resolution of 300 eV at 15 kev, and located at 90° to the incident beam in the plane of the electron orbit. In samples containing many elements, detection limits of a few ppm were achieved with 100 μm beams.

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Face-on SS 433 Stars as a Possible New Type of Extragalactic X-Ray Sources

Symposium - International Astronomical Union ◽

10.1017/s0074180900221165 ◽

2001 ◽

Vol 205 ◽

pp. 268-269 ◽

Cited By ~ 13

Author(s):

S. Fabrika ◽

A. Mescheryakov

Keyword(s):

X Rays ◽

Relativistic Jets ◽

Expected Frequency ◽

X Ray ◽

Ss 433 ◽

Sky Survey ◽

Supercritical Accretion ◽

The Face ◽

New Type ◽

Positive Correlations

The object SS433 is a well-known source of relativistic jets, which are formed in supercritical accretion disk. It is very probable that the disk has polar channels and their radiation is collimated (the photo-cones). A face-on SS433 object can appear as ultra-bright and highly variable X-ray source, Lx ˜ 1040 − 1042 erg/s. We discuss the properties of these hypothetical objects and their frequency expected in galaxies. We describe a search for such objects using the ROSAT All Sky Survey and RC3 catalog of galaxies. Among the total 418 positive correlations we find that 142 sources in S and Irr galaxies are unknown as AGNs. Nuclear sources among them still contain many AGNs. Non-nuclear (offset) sources are rather hard, their X-ray luminosities are 1039 − 1041 erg/s. Their observed frequency is about 4–5% per galaxy, that is in agreement with expected frequency of the face-on SS 433 stars. The only way to recognize such stars is their expected violent variability in X rays.

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Absorption and secondary scattering of X-rays with an off-axis small beam for a cylindrical sample geometry

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273318017710 ◽

2019 ◽

Vol 75 (2) ◽

pp. 362-369

Author(s):

Daniel C. Van Hoesen ◽

James C. Bendert ◽

Kenneth F. Kelton

Keyword(s):

Multiple Scattering ◽

Incident Beam ◽

Cylindrical Sample ◽

X Rays ◽

Beam Size ◽

X Ray ◽

Sample Geometry ◽

Integral Forms ◽

Secondary Scattering ◽

X Ray Absorption

Expressions for X-ray absorption and secondary scattering are developed for cylindrical sample geometries. The incident-beam size is assumed to be smaller than the sample and in general directed off-axis onto the cylindrical sample. It is shown that an offset beam has a non-negligible effect on both the absorption and multiple scattering terms, resulting in an asymmetric correction that must be applied to the measured scattering intensities. The integral forms of the corrections are first presented. A small-beam limit is then developed for easier computation.

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