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The approximation of asymmetric neutron powder diffraction peaks by sums of Gaussians
Author(s) -
Howard C. J.
Publication year - 1982
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889882012783
Subject(s) - asymmetry , neutron diffraction , powder diffractometer , gaussian , neutron , rietveld refinement , diffractometer , diffraction , computational physics , materials science , optics , physics , nuclear physics , particle physics , quantum mechanics , scanning electron microscope
Neutron powder diffractometers operating with large vertical counter acceptance angles produce diffraction patterns in which the peaks are shifted and broadened, and may become distinctly asymmetric. It is shown that a sum of Gaussians generally provides a good approximation to these peaks. The sum of Gaussians has been included as an optional description of the profile within an existing profile refinement program. In this application, the sum incorporates a single asymmetry parameter which can be estimated from the diffractometer geometry or determined in the refinement. It is recommended that, in describing asymmetric peaks, the sum of Gaussians be used in place of the simple Gaussian multiplied by Rietveld's semi‐empirical asymmetry factor.