Diffracted Beam Monochromators for Powder Diffractometry

1970 ◽  
Vol 14 ◽  
pp. 38-56
Author(s):  
E. M. Proctor ◽  
T. C. Furnas ◽  
W. F. Loranger
Keyword(s):  
Preferred Orientation ◽  
Signal To Noise ◽  
X Ray ◽  
Direct Beam ◽  
Vertical Divergence ◽  
Oriented Samples ◽  
Efficiency And Effectiveness ◽  
Slit System ◽  
Bent Crystals ◽  
Selection Of

AbstractThe efficiency and effectiveness of diffracted beam x-ray monochromators used in powder diffractometry have been described in so many ways that much confusion exists regarding their true performance. Although significant improvements in signal to noise ratios are readily achievable, and they offer a solution to the sample fluorescence problem, it is not without sacrifice to total intensity or achievable resolution or both. This paper discusses and describes a series of comparisons between filtered direct beam, LiF and graphite monochromators.These comparisons include the considerations necessary for the appropriate selection of diffracted beam slit system, the effect of vertical divergence as a function of two theta for singly bent crystals, the effects of a non-uniformity of contribution over the length of the crystal, and the geometry necessary for the singly bent and doubly bent crystals. The total intensity and the resolution of LiF and graphite are discussed, in particular, it is noted that the performance of monochromators with randomly oriented samples is quite different than their performance with samples showing preferred orientation or grain effects.A new diffracted beam monochromator based on the Rowland focusing geometry is described.

scholarly journals Aspects of direct phasing in femtosecond nanocrystallography

2014 ◽  
Vol 369 (1647) ◽  
pp. 20130498 ◽  
Author(s):  
Rick P. Millane ◽  
Joe P. J. Chen
Keyword(s):  
Free Electron Laser ◽  
Phase Retrieval ◽  
Laser Diffraction ◽  
Intensity Data ◽  
Noise Levels ◽  
Signal To Noise ◽  
X Ray ◽  
Unit Cells ◽  
Diffraction Patterns ◽  
Selection Of

X-ray free-electron laser diffraction patterns from protein nanocrystals provide information on the diffracted amplitudes between the Bragg reflections, offering the possibility of direct phase retrieval without the use of ancillary experimental data. Proposals for implementing direct phase retrieval are reviewed. These approaches are limited by the signal-to-noise levels in the data and the presence of different and incomplete unit cells in the nanocrystals. The effects of low signal to noise can be ameliorated by appropriate selection of the intensity data samples that are used. The effects of incomplete unit cells may be small in some cases, and a unique solution is likely if there are four or fewer molecular orientations in the unit cell.

X-ray powder transmission diffractometry determination of mica polytypes: method and application to natural samples

Clay Minerals ◽  
1985 ◽  
Vol 20 (2) ◽  
pp. 231-248 ◽  
Author(s):  
A. Wiewióra ◽  
Z. Weiss
Keyword(s):  
Computer Program ◽  
Structural Data ◽  
Preferred Orientation ◽  
X Ray ◽  
Space Groups ◽  
Oriented Samples

AbstractTransmission powder patterns of random and of highly oriented samples of natural micas have been recorded and compared with those calculated from structural data with the aid of the DIFK computer program modified to correct for preferred orientation. Intensities calculated from structural data for random and for highly oriented samples (symmetrical and oblique settings) are presented for 1M, 2M1, 2M2, 3T polytypes of muscovite, 1M, 2M1, 3T polytypes of paragonite and 1M (C2/m and C2 space groups), 2M1, 2M2, 3T polytypes of lepidolite.

Failure Analysis Enhancement by Incorporating a Compact Scan Diagnosis System

2014 ◽  
Author(s):  
Rommel Estores ◽  
Pascal Vercruysse ◽  
Karl Villareal ◽  
Eric Barbian ◽  
Ralph Sanchez ◽  
...  
Keyword(s):  
Data Analysis ◽  
Failure Analysis ◽  
Real Analysis ◽  
Failure Data ◽  
Analysis Methodology ◽  
Efficiency And Effectiveness ◽  
Scan Chain ◽  
On Chip ◽  
Analysis Environment ◽  
Selection Of

Abstract The failure analysis community working on highly integrated mixed signal circuitry is entering an era where simultaneously System-On-Chip technologies, denser metallization schemes, on-chip dissipation techniques and intelligent packages are being introduced. These innovations bring a great deal of defect accessibility challenges to the failure analyst. To contend in this era while aiming for higher efficiency and effectiveness, the failure analysis environment must undergo a disruptive evolution. The success or failure of an analysis will be determined by the careful selection of tools, data and techniques in the applied analysis flow. A comprehensive approach is required where hardware, software, data analysis, traditional FA techniques and expertise are complementary combined [1]. This document demonstrates this through the incorporation of advanced scan diagnosis methods in the overall analysis flow for digital functionality failures and supporting the enhanced failure analysis methodology. For the testing and diagnosis of the presented cases, compact but powerful scan test FA Lab hardware with its diagnosis software was used [2]. It can therefore easily be combined with the traditional FA techniques to provide stimulus for dynamic fault localizations [3]. The system combines scan chain information, failure data and layout information into one viewing environment which provides real analysis power for the failure analyst. Comprehensive data analysis is performed to identify failing cells/nets, provide a better overview of the failure and the interactions to isolate the fault further to a smaller area, or to analyze subtle behavior patterns to find and rationalize possible faults that are otherwise not detected. Three sample cases will be discussed in this document to demonstrate specific strengths and advantages of this enhanced FA methodology.

Ultra-fast selection of grasping points

2013 ◽  
Vol 110 (7) ◽  
pp. 1484-1489 ◽  
Author(s):  
D. Voudouris ◽  
J. B. J. Smeets ◽  
E. Brenner
Keyword(s):  
Reaction Times ◽  
Preferred Orientation ◽  
Reach To Grasp ◽  
Contact Points ◽  
Selection Of

To grasp an object one needs to determine suitable positions on its surface for placing the digits and to move the digits to those positions. If the object is displaced during a reach-to-grasp movement, the digit movements are quickly adjusted. Do these fast adjustments only guide the digits to previously chosen positions on the surface of the object, or is the choice of contact points also constantly reconsidered? Subjects grasped a ball or a cube that sometimes rotated briefly when the digits started moving. The digits followed the rotation within 115 ms. When the object was a ball, subjects quickly counteracted the initial following response by reconsidering their choice of grasping points so that the digits ended at different positions on the rotated surface of the ball, and the ball was grasped with the preferred orientation of the hand. When the object was a cube, subjects sometimes counteracted the initial following response to grasp the cube by a different pair of sides. This altered choice of grasping points was evident within ∼160 ms of rotation onset, which is shorter than regular reaction times.

scholarly journals Short-pulse laser-driven x-ray radiography

2016 ◽  
Vol 4 ◽  
Author(s):  
E. Brambrink ◽  
S. Baton ◽  
M. Koenig ◽  
R. Yurchak ◽  
N. Bidaut ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Short Pulse ◽  
Incident Angle ◽  
Laboratory Astrophysics ◽  
Signal To Noise ◽  
High Quality ◽  
X Ray ◽  
Short Pulse Laser ◽  
Short Pulse Lasers

We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pulse laser on the x-ray source target. The setup has been tested with various x-ray source target materials and different laser wavelengths. Signal to noise ratios are presented as well as achieved spatial resolutions. The high quality of our technique is illustrated on a plasma flow radiograph obtained during a laboratory astrophysics experiment on POLARs.

Absorption Corrections in X‐Ray Studies of Preferred Orientation

1949 ◽  
Vol 20 (3) ◽  
pp. 173-174 ◽  
Author(s):  
R. Smoluchowski ◽  
R. W. Turner
Keyword(s):  
Preferred Orientation ◽  
X Ray

NbN Thin Film of Alternating Textures

2017 ◽  
Vol 898 ◽  
pp. 1431-1437
Author(s):  
Hong Yang Shao ◽  
Kan Zhang ◽  
Yi Dan Zhang ◽  
Mao Wen ◽  
Wei Tao Zheng
Keyword(s):  
Deposition Time ◽  
Peak Position ◽  
Preferred Orientation ◽  
Intrinsic Stress ◽  
Competitive Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Orientation Distributions ◽  
Different Thickness ◽  
Deposited Films

The δ-NbN thin films with different thickness have been prepared by reactive magnetron sputtering at different deposition time and exhibited alternating textures between (111) and (200) orientations as a function of thickness. In addition, the grain size, peak position, morphology, residual stress and orientation distributions of the deposited films were explored by X-ray diffraction, low-angel X-ray reflectivity, scanning electron microscopy and surface profiler. The film deposited at 300 s showed a (111) preferred orientation, changing to (200) preferred orientation at 600 s, and exhibited alternating textures between (111) and (200) preferred orientations. With further increasing deposition time, in which (200) peak position and the full width at half maximum of (111) peak also displayed a trend of alternating variation with varying deposition time. The intrinsic stress for δ-NbN films calculated by Stoney equation alternately changed with alternating textures, in which (111) orientation always takes place at relatively high intrinsic stress state and vice versa. Meanwhile, the film with (111) preferred orientation showed higher density than (200) preferred orientation. The film deposited at 4800 s owned a mixed texture of (111) and (200), showing an anisotropy distribution of (111)-oriented and (200)-oriented grains, while film deposited at 7200 s owned a strong (200) texture, displaying an isotropy distribution of (200)-oriented grains. The competitive growth between (111)-oriented and (200)-oriented grains was responsibility for alternating texture.

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