Friedel pair - Revision history

BrianMcMahon: Added German and Spanish translations (U. Mueller)

2017-11-13T13:42:39Z

Added German and Spanish translations (U. Mueller)

BrianMcMahon: Style edits to align with printed edition

2017-05-15T11:40:11Z

Style edits to align with printed edition

MassimoNespolo: Ja

2015-06-23T05:01:27Z

HowardFlack: /* Definition */

2013-10-11T15:23:06Z

‎Definition

HowardFlack: /* Definition */

2013-10-11T14:02:42Z

‎Definition

HowardFlack: /* Definition */

2013-10-11T13:59:33Z

‎Definition

GervaisChapuis at 18:49, 26 August 2013

2013-08-26T18:49:41Z

GervaisChapuis at 18:43, 26 August 2013

2013-08-26T18:43:00Z

GiovanniFerraris at 14:28, 28 March 2006

2006-03-28T14:28:08Z

AndreAuthier at 08:01, 26 March 2006

2006-03-26T08:01:51Z

← Older revision		Revision as of 13:42, 13 November 2017
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−	<~~Font~~ color="blue">Paire de Friedel</~~Font~~> (''Fr''). <~~Font~~ color="black">Coppia di Friedel</~~Font~~> (''It''). <~~Font~~ color="purple">フリーデル対</~~Font~~> (''Ja'').	+	<font color="blue">Paire de Friedel</font> (''Fr''). <font color="red">Friedelpaar</font> (''Ge''). <font color="black">Coppia di Friedel</font> (''It''). <font color="purple">フリーデル対</font> (''Ja''). <font color="green">Par de Friedel</font> (''Sp'').

	== Definition ==		== Definition ==

@@ Line 3: / Line 3: @@
 == 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 either if the crystal structure is centrosymmetric or if there is no [[Resonant_scattering|resonant scattering]], but differ otherwise. [[Friedel's law]] then does not hold. For crystals with a non-centrosymmetric structure and significant resonant scattering, equivalent reflections generated by the symmetry operations of the point group of the crystal have intensities different from those of equivalent reflections generated by the introduction of an additional inversion centre in normal scattering. Friedel, or Bijvoet pairs are used in the resolution of the phase problem for the solution of crystal structures and in the determination of absolute structure.
+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 either if the crystal structure is centrosymmetric or if there is no [[Resonant_scattering|resonant scattering]], but differ otherwise. [[Friedel's law]] then does not hold. For crystals with a non-centrosymmetric structure and significant resonant scattering, equivalent reflections generated by the symmetry operations of the point group of the crystal have intensities different from those of equivalent reflections generated by the introduction of an additional inversion centre in normal scattering. Friedel, or Bijvoet, pairs are used in the resolution of the phase problem for the solution of crystal structures and in the determination of absolute structure.
 == History ==
-The use of Friedel's pairs for helping in phase determinations was suggested by Bijvoet J. M., Peerdeman A. F. & van Bommel A. J. (1951), ''Determination of the absolute configuration of optically active compounds by means of X-rays''. ''Nature (London)'', '''168''', 271–272.
+The use of Friedel's pairs for helping in phase determinations was suggested by Bijvoet, J. M., Peerdeman, A. F. and van Bommel, A. J. (1951), ''Determination of the absolute configuration of optically active compounds by means of X-rays''. ''Nature (London)'', '''168''', 271–272.
 == See also ==
-[[Friedel's law]]<br>
+*[[Friedel's law]]
-Section 2.4.3 of ''International Tables of Crystallography, Volume B''<br>
+*Chapter 2.4.3 of ''International Tables for Crystallography, Volume B''
-Section 4.2.6 of ''International Tables of Crystallography, Volume C''<br>
+*Chapter 4.2.6 of ''International Tables for Crystallography, Volume C''
 [[Category:X-rays]]<br>

← Older revision		Revision as of 05:01, 23 June 2015
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−	<Font color="blue"> Paire de Friedel </Font> (''Fr'').<Font color="black"> Coppia di Friedel </Font>(''It'')	+	<Font color="blue">Paire de Friedel</Font> (''Fr''). <Font color="black">Coppia di Friedel</Font> (''It''). <Font color="purple">フリーデル対</Font> (''Ja'').
−

	== Definition ==		== Definition ==

@@ Line 4: / Line 4: @@
 == 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 either if the crystal structure is centrosymmetric or if there is no [[Anomalous_dispersion|resonant scattering]], but differ otherwise. [[Friedel's law]] then does not hold. For crystals with a non-centrosymmetric structure and significant resonant scattering, equivalent reflections generated by the symmetry operations of the point group of the crystal have intensities different from those of equivalent reflections generated by the introduction of an additional inversion centre in normal scattering. Friedel, or Bijvoet pairs are used in the resolution of the phase problem for the solution of crystal structures and in the determination of absolute structure.
+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 either if the crystal structure is centrosymmetric or if there is no [[Resonant_scattering|resonant scattering]], but differ otherwise. [[Friedel's law]] then does not hold. For crystals with a non-centrosymmetric structure and significant resonant scattering, equivalent reflections generated by the symmetry operations of the point group of the crystal have intensities different from those of equivalent reflections generated by the introduction of an additional inversion centre in normal scattering. Friedel, or Bijvoet pairs are used in the resolution of the phase problem for the solution of crystal structures and in the determination of absolute structure.
 == History ==

@@ Line 4: / Line 4: @@
 == 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 either if the crystal structure is centrosymmetric or if there is no [[Anomalous_dispersion|resonant scattering]], but differ otherwise. [[Friedel's law]] then does not hold. For crystals with a non-centrosymmetric structure and significant resonant scattering, equivalent reflections generated by the symmetry operations of the point group of the crystal have intensities different from those of equivalent reflections generated by the introduction of an additional inversion centre in normal scattering. Friedel, or Bijvoet pairs are used in the resolution of the phase problem for the solution of crystal structures.
+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 either if the crystal structure is centrosymmetric or if there is no [[Anomalous_dispersion|resonant scattering]], but differ otherwise. [[Friedel's law]] then does not hold. For crystals with a non-centrosymmetric structure and significant resonant scattering, equivalent reflections generated by the symmetry operations of the point group of the crystal have intensities different from those of equivalent reflections generated by the introduction of an additional inversion centre in normal scattering. Friedel, or Bijvoet pairs are used in the resolution of the phase problem for the solution of crystal structures and in the determination of absolute structure.
 == History ==

← Older revision		Revision as of 14:28, 28 March 2006
Line 1:		Line 1:
−	<Font color="blue"> Paire de Friedel </Font> (''Fr'').	+	<Font color="blue"> Paire de Friedel </Font> (''Fr'').<Font color="black"> Coppia di Friedel </Font>(''It'')
		+

	== Definition ==		== Definition ==

← Older revision		Revision as of 08:01, 26 March 2006
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	Section 2.4.3 of ''International Tables of Crystallography, Volume B''<br>		Section 2.4.3 of ''International Tables of Crystallography, Volume B''<br>
	Section 4.2.6 of ''International Tables of Crystallography, Volume C''<br>		Section 4.2.6 of ''International Tables of Crystallography, Volume C''<br>
		+
		+	[[Category:X-rays]]<br>