Electronic Resource
[S.l.]
:
International Union of Crystallography (IUCr)
Acta crystallographica
43 (1987), S. 173-179
ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The invariant phases of large numbers of germanium triplets, consisting of one forbidden and two permitted reflections, have been determined experimentally. The forbidden reflections include members of the forms {200}, {222}, {420} and {442}. Phase effects in triplets containing members of the ultra-weak (forbidden) {622} and {640} were detected but were too weak to provide reliable phase indications. The phases of all triplets which include a forbidden reflection and the {\bar 3}{\bar 1}{\bar 1} reflection are observed to be negative. The phases of individual forbidden reflections, whose indices are described as summing to (4n - 2), are equal to (-1)n. The imaginary part of the dispersion correction to the atomic form factors is relatively large (0.89 for Cu Kα1 radiation): it makes significant contributions to the structure factors and the phases of the vanishingly weak forbidden reflections.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0108767387099616
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