ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The refraction effect associated with an off-Bragg diffracted beam in high-energy transmission electron diffraction is analysed. It is found that the wave vectors of Bloch-wave components of a beam associated with a finite excitation error are significantly shortened or lengthened as a consequence of dynamic scattering, with the direction of change being determined by the sign of the excitation error. By consideration of the dark-field image formed from the off-Bragg reflection and its associated refractive fine structure it is shown that a top-bottom effect exists, which can be demonstrated by comparing images of the same field for positive and negative excitation errors. This is discussed in two dimensions for a crystal of triangular cross section and one horizontal face, in the two orientations of apex up and apex down, with numerical and graphical evaluations from linear three-beam diffraction.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S010876738800741X
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