# Difference between revisions of "Friedel pair"

### From Online Dictionary of Crystallography

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== Definition == | == Definition == | ||

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+ | The couple of reflections ''h'', ''k'', ''l'' and <math>{\bar h}, {\bar k}, {\bar l}</math> is called a Friedel pair, or Bijvoet pair. Their intensities are equal if there is no absorption, but differ otherwise. [[Friedel's law]] then does not hold. Generally speaking, when absorption is present, equivalent reflections generated by the symmetry elements in the crystal have intensities different from those of equivalent reflections generated by the introduction of an additional inversion centre in normal scattering. | ||

== See also == | == See also == | ||

[[Friedel's law]]<br> | [[Friedel's law]]<br> | ||

− | Section 4.2.6 of ''International Tables of Crystallography, Volume C'' | + | Section 2.4.3 of ''International Tables of Crystallography, Volume B''<br> |

+ | Section 4.2.6 of ''International Tables of Crystallography, Volume C''<br> |

## Revision as of 07:55, 25 March 2006

Paire de Friedel (*Fr*).

## Definition

The couple of reflections *h*, *k*, *l* and [math]{\bar h}, {\bar k}, {\bar l}[/math] is called a Friedel pair, or Bijvoet pair. Their intensities are equal if there is no absorption, but differ otherwise. Friedel's law then does not hold. Generally speaking, when absorption is present, equivalent reflections generated by the symmetry elements in the crystal have intensities different from those of equivalent reflections generated by the introduction of an additional inversion centre in normal scattering.

## See also

Friedel's law

Section 2.4.3 of *International Tables of Crystallography, Volume B*

Section 4.2.6 of *International Tables of Crystallography, Volume C*