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Dynamical scattering and electron diffraction from thin polymer lamellar crystals - poly(tert-butylethylene sulfide)

Dynamical scattering and electron diffraction from thin polymer lamellar crystals -... Strong violations of Friedel symmetry are observed in hk0 electron diffraction patterns from lamellar crystals of poly(tert-butylethylene sulfide) obtained at 120 kV. These deviations are largely explained by a multislice dynamical scattering calculation based on the crystal structure model. Further improvement is found when a secondary scattering component is added, in keeping with a perfect crystallite thickness less than that of the lamellar thickness. Despite the multiple-scattering perturbations, the frustrated chain packing can still be determined by direct methods followed by Fourier refinement. However, the Friedel-related intensities must be averaged before calculation of normalized structure factors. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Acta Crystallographica Section A: Foundations of Crystallography International Union of Crystallography

Dynamical scattering and electron diffraction from thin polymer lamellar crystals - poly(tert-butylethylene sulfide)

Dynamical scattering and electron diffraction from thin polymer lamellar crystals - poly(tert-butylethylene sulfide)


Abstract

Strong violations of Friedel symmetry are observed in hk0 electron diffraction patterns from lamellar crystals of poly(tert-butylethylene sulfide) obtained at 120 kV. These deviations are largely explained by a multislice dynamical scattering calculation based on the crystal structure model. Further improvement is found when a secondary scattering component is added, in keeping with a perfect crystallite thickness less than that of the lamellar thickness. Despite the multiple-scattering perturbations, the frustrated chain packing can still be determined by direct methods followed by Fourier refinement. However, the Friedel-related intensities must be averaged before calculation of normalized structure factors.

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References (28)

Publisher
International Union of Crystallography
Copyright
Copyright (c) 1999 International Union of Crystallography
Subject
electron diffraction, phase determination, dynamical scattering
ISSN
0108-7673
eISSN
1600-5724
DOI
10.1107/S0108767399004250
Publisher site
See Article on Publisher Site

Abstract

Strong violations of Friedel symmetry are observed in hk0 electron diffraction patterns from lamellar crystals of poly(tert-butylethylene sulfide) obtained at 120 kV. These deviations are largely explained by a multislice dynamical scattering calculation based on the crystal structure model. Further improvement is found when a secondary scattering component is added, in keeping with a perfect crystallite thickness less than that of the lamellar thickness. Despite the multiple-scattering perturbations, the frustrated chain packing can still be determined by direct methods followed by Fourier refinement. However, the Friedel-related intensities must be averaged before calculation of normalized structure factors.

Journal

Acta Crystallographica Section A: Foundations of CrystallographyInternational Union of Crystallography

Published: Sep 1, 1999

Keywords: electron diffraction; phase determination; dynamical scattering.

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