Valence charge density in grey tin: X-ray determination of the (222) "forbidden" reflection and its temperature dependence

1975 ◽  
Vol 11 (2) ◽  
pp. 793-797 ◽  
Author(s):  
D. H. Bilderback ◽  
R. Colella
Keyword(s):  
Charge Density ◽  
Temperature Dependence ◽  
X Ray

Bestimmung der Röntgen-Debye-Temperatur aus dem Borrmann-Effekt in Germanium / Determination of the X-ray Debye Temperature in Germanium by Means of the Borrmann Effect

1973 ◽  
Vol 28 (7) ◽  
pp. 1204-1213 ◽  
Author(s):  
J. Ludewig
Keyword(s):  
Temperature Dependence ◽  
Compton Scattering ◽  
Debye Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Perfect Crystal ◽  
Photoelectric Absorption ◽  
Temperature Dependent ◽  
X Ray

The anomal transmission of CuK radiation through "thick"' perfect crystal slices of Germanium is strongly temperature dependent. This temperature dependence was measured between 293 and 6 K in the (220) symmetric Laue case and used to evaluate the Debye temperature θM . The wellknown uncorrected value θ′M = 290K was obtained near room temperature. Taking into account TDS and Compton scattering in addition to the photoelectric absorption the corrected value θM = 294 or 296 K was found, depending on the source of data. With decreasing temperature the corrected θM increases slightly up to a maximum at very low temperatures, as predicted by Batterman and Chipman and by Salter.

The electronic structure of the 3d transition metals

1981 ◽  
Vol 14 (6) ◽  
pp. 401-416 ◽  
Author(s):  
R. J. Weiss ◽  
G. Mazzone
Keyword(s):  
Charge Density ◽  
Cohesive Energy ◽  
Direct Determination ◽  
Momentum Density ◽  
Free Atom ◽  
Metallic Elements ◽  
X Ray ◽  
X Ray Scattering ◽  
Seitz Cell

The measurements and calculations of the charge, spin and momentum density of the metallic elements Ti to Ni are examined. Both the Compton profiles (momentum density) and X-ray scattering factors (charge density) are shown to provide a direct determination of the cohesive energy. It generally appears that the 3d spin density is contracted relative to the free atom while the 3d charge density builds up at the Wigner–Seitz cell boundary relative to the free atom particularly near the bottom of the band. No theoretical calculation is available which evaluates charge, spin and momentum density as well as cohesive energy. In addition, a significant disparity between theory and experiment exists for the momentum and charge density anisotropies in the b.c.c. metals. Suggested areas for further work are given.

scholarly journals On the temperature dependence of H-Uisoin the riding hydrogen model

2014 ◽  
Vol 70 (4) ◽  
pp. 309-316 ◽  
Author(s):  
Jens Lübben ◽  
Christian Volkmann ◽  
Simon Grabowsky ◽  
Alison Edwards ◽  
Wolfgang Morgenroth ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Diffraction Data ◽  
Lone Pair ◽  
Precise Determination ◽  
Neutron Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lone Pair Electron ◽  
Oniom Approach

The temperature dependence of H-UisoinN-acetyl-L-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-Uisobelow 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found.

Lateral resolution of the electron microbeam analysis

1978 ◽  
Vol 36 (1) ◽  
pp. 542-543
Author(s):  
H.J. Dudek
Keyword(s):  
Quantitative Analysis ◽  
Depth Resolution ◽  
Lateral Resolution ◽  
Cylindrical Particle ◽  
Correction Procedure ◽  
X Ray ◽  
Element Concentrations ◽  
Microbeam Analysis ◽  
The Matrix

The chemical inhomogenities in modern materials such as fibers, phases and inclusions, often have diameters in the region of one micrometer. Using electron microbeam analysis for the determination of the element concentrations one has to know the smallest possible diameter of such regions for a given accuracy of the quantitative analysis.In th is paper the correction procedure for the quantitative electron microbeam analysis is extended to a spacial problem to determine the smallest possible measurements of a cylindrical particle P of high D (depth resolution) and diameter L (lateral resolution) embeded in a matrix M and which has to be analysed quantitative with the accuracy q. The mathematical accounts lead to the following form of the characteristic x-ray intens ity of the element i of a particle P embeded in the matrix M in relation to the intensity of a standard S

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

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