Systematic absences

From Online Dictionary of Crystallography

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== Definition ==
== Definition ==
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One speaks of ''systematic absences'' or ''extinctions'' when the structure factor is zero, due either to the centring of the lattice or to the presence of glide or screw symmetry elements. Conversely, the conditions for a reflection to exist and not to be systematically absent, are called [[reflection conditions]].
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== See also ==
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[[reflection conditions]]<br>
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Sections 2.2.13 and 12.3.5 of the International Tables of Crystallography (Volume A)''<br>

Revision as of 08:01, 17 April 2006

absences systématiques (Fr).

Definition

One speaks of systematic absences or extinctions when the structure factor is zero, due either to the centring of the lattice or to the presence of glide or screw symmetry elements. Conversely, the conditions for a reflection to exist and not to be systematically absent, are called reflection conditions.

See also

reflection conditions
Sections 2.2.13 and 12.3.5 of the International Tables of Crystallography (Volume A)