In:
Proceedings, annual meeting, Electron Microscopy Society of America, Cambridge University Press (CUP), Vol. 39 ( 1981-08), p. 30-31
Abstract:
The failure of the kinematic scattering approximation, and also of the “weak phase object” approximation, may represent one of the most serious problems in the interpretation of high resolution electron diffraction data and electron microscope images. The existence and behavior of dynamical diffraction effects are well characterized in materials science applications, but the possible influence of dynamical effects is still not completely understood in applications involving unstained biological materials, which are characterized by low atomic number and large unit cells. We have previously reported numerical calculations in which we have explored the conditions under which the kinematic approximation would be valid, to an acceptable level of accuracy, for complex biological structures. The known structure of a protein, cytochrome b 5 , was used as a test object, and the Cowley-Moodie multislice method was used to calculate the “exact” dynamical diffracted waves. For 100 keV electrons it has been found that the kinematic approximation is acceptable up to a specimen thickness of about 150 Å, as judged by the crystallographic “R-value”, by the appearance of the difference Patterson function (for heavy atom derivatives), and by the number of wrong phases that are derived from the dynamical diffraction intensities.
Type of Medium:
Online Resource
ISSN:
0424-8201
,
2690-1315
DOI:
10.1017/S0424820100096874
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
1981
SSG:
11
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