X-ray phase determination of solid paraffins in asphalts

1983 ◽  
Vol 19 (7) ◽  
pp. 366-368
Author(s):  
T. G. Biktimirova ◽  
S. L. Aleksandrova ◽  
V. V. Fryazinov
Keyword(s):  
Phase Determination ◽  
X Ray

Phase determination of X-ray reflections in a quasicrystal

1993 ◽  
Vol 49 (4) ◽  
pp. 600-605 ◽  
Author(s):  
H. Lee ◽  
R. Colella ◽  
L. D. Chapman
Keyword(s):  
Phase Determination ◽  
X Ray

scholarly journals Direct Phase Determination of Surface In-plane Reflection of Thin films by X-ray Grazing Incident Three-wave Resonance Diffraction

2000 ◽  
Vol 56 (s1) ◽  
pp. s403-s403 ◽  
Author(s):  
Y.-S. Huang ◽  
C.-S. Chao ◽  
C.-H. Hsu ◽  
Y. P. Stetsko ◽  
C.-Y. Hung ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Determination ◽  
X Ray ◽  
Wave Resonance

Study of YBa2Cu3O7−x reaction kinetics by Rietveld method

2001 ◽  
Vol 16 (1) ◽  
pp. 25-29
Author(s):  
Maria Cristina Comunian Ferraz ◽  
Heitor Cury Basso ◽  
Yvonne P. Mascarenhas
Keyword(s):  
Reaction Kinetics ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Analysis Procedure ◽  
Powder Diffraction Data ◽  
Phase Determination ◽  
Reaction Route ◽  
Formation Reaction ◽  
X Ray

Using a recent proposed analysis procedure for quantitative phase determination by X-ray powder diffraction, YBa2Cu3O7−x solid state formation reaction kinetics at 900 °C was studied. Although there was the presence of partial amorphous components, it was possible to determine a reaction route for the synthesis of the title compound from X-ray powder diffraction data collected at various stages of the thermal treatment and using the Rietveld method for the quantitative determination of the phase composition

scholarly journals Phase determination of x-ray reflection coefficients

2000 ◽  
Vol 62 (15) ◽  
pp. 10377-10382 ◽  
Author(s):  
K.-M. Zimmermann ◽  
M. Tolan ◽  
R. Weber ◽  
J. Stettner ◽  
A. K. Doerr ◽  
...  
Keyword(s):  
Reflection Coefficients ◽  
Phase Determination ◽  
X Ray

Use of direct phasing in determination of atomic co-ordinates of anthanthrene, C22H12

1995 ◽  
Vol 53 ◽  
pp. 154-155
Author(s):  
C. E. Leslie ◽  
J. R. Fryer ◽  
C. J. Gilmore ◽  
W. Nicolson
Keyword(s):  
Organic Molecule ◽  
Room Temperature ◽  
Maximum Entropy Method ◽  
Likelihood Estimation ◽  
Entropy Method ◽  
Organic Crystals ◽  
Phase Determination ◽  
X Ray ◽  
Lower Beam

Imaging of organic crystals in the electron microscope is limited by their sensitivity to the electron beam, with even the most stable molecules only giving a resolution of ~3Å. By contrast, electron diffraction requires a lower beam intensity, and so can give much better resolution, down to ~lÅ under favourable conditions. Intensities may be measured directly from the diffraction pattern, and the phase determination problem can be surmounted by applying the maximum entropy method, which chooses phases by likelihood estimation.It was decided to apply this method to the organic molecule anthanthrene, C22H12 (fig. 1), since x-ray studies found that the crystals were monoclinic with a = 12.10Å, b = 10.34Å, c = 10.74Å, β = 92.2°, space group P21/a and Z = 4, but no details of the atomic co-ordinates were given in the literature. A previous study of the molecule, using KC1 as the substrate, produced epitaxial layers showing the acprojection being most common at room temperature.

Direct phase determination and refinement in the electron crystallography of small structures

1993 ◽  
Vol 51 ◽  
pp. 684-685
Author(s):  
Douglas L. Dorset ◽  
Mary P. McCourt
Keyword(s):  
Electron Diffraction ◽  
Scattering Theory ◽  
Heavy Atom ◽  
Intensity Data ◽  
Phase Information ◽  
Diffraction Intensity ◽  
Phase Determination ◽  
X Ray ◽  
Primary Extinction

The use of electron diffraction intensity data for quantitative determination of crystal structures was largely pioneered by Vainshtein, Pinsker and their co-workers, as recently reviewed, and was shown to produce results consistent with more typical X-ray structure analyses. Despite these encouraging results for a number of representative inorganic and organic materials, it is accurate to say that the technique has not been widely accepted by the crystallographic community. This is probably because, in several of the early analyses, contemporary X-ray structure results were used to provide heavy atom positions, thus providing much of the crystallographic phase information. Since it is also known that correct phases, combined with even scrambled structure factor amplitudes, will lead to a Fourier map that appears to be ’correct’, it is commonly (but incorrectly) thought that no ab initio electron diffraction determinations have been carried out for previously unsolved structures. In addition, the very complexity of n-beam dynamical scattering theory compared to ’primary extinction’ corrections has dampened enthusiasm to continue this work.

Ta6Br122+, a tool for phase determination of large biological assemblies by X-ray crystallography

1997 ◽  
Vol 270 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Jörg Knäblein ◽  
Torsten Neuefeind ◽  
Frank Schneider ◽  
Andreas Bergner ◽  
Albrecht Messerschmidt ◽  
...  
Keyword(s):  
Phase Determination ◽  
X Ray ◽  
X Ray Crystallography

Direct phase determination of large macromolecular crystals using three-beam x-ray interference

1991 ◽  
Vol 67 (22) ◽  
pp. 3113-3116 ◽  
Author(s):  
Shih-Lin Chang ◽  
H. E. King ◽  
Mau-Tzai Huang ◽  
Yan Gao
Keyword(s):  
Phase Determination ◽  
X Ray
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