Short Range Triplet Correlations in Krypton Near the Critical Point

1973 ◽  
Vol 51 (18) ◽  
pp. 1965-1970 ◽  
Author(s):  
D. J. Winfield ◽  
P. A. Egelstaff
Keyword(s):  
Correlation Function ◽  
Neutron Diffraction ◽  
Diffraction Data ◽  
Structure Factor ◽  
Short Range ◽  
Neutron Diffraction Data ◽  
Pressure Derivative ◽  
First Approximation ◽  
Triplet Correlation ◽  
Triplet Correlation Function

Neutron diffraction data have been taken for two states on the 218 °K isotherm of krypton. The isothermal pressure derivative of the fluid structure factor is interpreted in terms of the triplet correlation function using an expansion due to Abe. It is concluded that three terms in Abe's expansion explain the data to a first approximation, but significant discrepancies remain.

scholarly journals Use of Extinction Corrections in Neutron Diffraction Experiments

1988 ◽  
Vol 41 (3) ◽  
pp. 383 ◽  
Author(s):  
A Delapalme
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Experimental Evidence ◽  
Diffraction Data ◽  
Structure Factor ◽  
Lorentz Factor ◽  
Relative Importance ◽  
Diffraction Experiment ◽  
Neutron Diffraction Data ◽  
Neutron Diffraction Experiment

The study of extinction by neutrons reveals many features of the extinction problem: theory and practical cases, polarised and unpolarised neutron cases. Special attention is given to the usual extinction corrections for neutron diffraction experiments, showing the relative importance of structure factor, wavelength, Lorentz factor, mosaic and the path of neutrons through the crystal. Two problems are reviewed: (a) how to detect the presence of extinction in both cases of a single crystal experiment with polarised and unpolarised neutrons; and (b) after experimental evidence for extinction in a neutron diffraction experiment, how to follow a reliable way to correct the neutron diffraction data in both cases of polarised and unpolarised neutron experiments. Some examples are given.

Probing the triplet correlation function in liquid water by experiments and molecular simulations

2017 ◽  
Vol 19 (4) ◽  
pp. 3265-3278 ◽  
Author(s):  
Debdas Dhabal ◽  
Kjartan Thor Wikfeldt ◽  
Lawrie B. Skinner ◽  
Charusita Chakravarty ◽  
Hemant K. Kashyap
Keyword(s):  
Correlation Function ◽  
Liquid Water ◽  
Molecular Simulations ◽  
Diffraction Experiment ◽  
X Ray Diffraction ◽  
Pressure Derivative ◽  
X Ray ◽  
Three Body ◽  
Triplet Correlation ◽  
Triplet Correlation Function

Three-body information of liquid water is extracted using X-ray diffraction experiment as well as in molecular simulations via isothermal pressure derivative of structure factor term.

A general structure factor formalism for interpreting accurate X-ray and neutron diffraction data

1967 ◽  
Vol 298 (1454) ◽  
pp. 255-263 ◽  
Keyword(s):  
Neutron Diffraction ◽  
Diffraction Data ◽  
Structure Factor ◽  
General Structure ◽  
Atomic Charge ◽  
Neutron Diffraction Data ◽  
X Ray ◽  
Librational Motion ◽  
Atomic Scattering ◽  
Complex Temperature

The interpretation of X-ray and neutron diffraction data in accurate studies of crystal and molecular structure requires the development of a new structure factor formalism. The formalism normally employed in structure analysis fails to recognize antisymmetric features associated with nonspherical atomic charge distributions and with anharmonic components of the atomic vibration amplitudes. Both these antisymmetric features can be incorporated readily in the analysis of diffraction data by using a general formalism involving complex atomic scattering factors and complex temperature factors. Some implications of the general formalism are discussed. Relations between atomic motions and static positions are considered in terms of equilibrium and time-averaged concepts, and the case of librational motion is cited to illustrate the relation of these concepts to the type of vibrational approximation employed in data analysis. The discussion is extended to general considerations of the atomic scattering powers, and approximations in the customary handling of these quantities are noted.

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