Sample orientation - Revision history

KevinYager: /* See Also */

2019-07-08T15:41:58Z

‎See Also

KevinYager: /* Reciprocal-space */

2015-01-24T15:18:40Z

‎Reciprocal-space

KevinYager: /* See Also */

2015-01-12T21:22:16Z

‎See Also

KevinYager: /* Reconstruction */

2015-01-12T21:22:04Z

‎Reconstruction

KevinYager at 23:07, 16 December 2014

2014-12-16T23:07:04Z

KevinYager: /* See Also */

2014-11-03T13:27:08Z

‎See Also

KevinYager: /* Reconstruction */

2014-09-30T02:04:04Z

‎Reconstruction

KevinYager: Created page with "For isotropic materials, the orientation of the sample with respect to the beam does not matter. However, for any sample that is anisotropic the '''sample orientation''' will ..."

2014-09-18T14:37:21Z

Created page with "For isotropic materials, the orientation of the sample with respect to the beam does not matter. However, for any sample that is anisotropic the '''sample orientation''' will ..."

New page

For isotropic materials, the orientation of the sample with respect to the beam does not matter. However, for any sample that is anisotropic the '''sample orientation''' will strongly influence the scattering pattern. This effect is relevant for any intrinsically anisotropic material, including crystals and aligned bulk materials (liquid crystals, stretched polymers, etc.). Any material which has broken symmetry will also be anisotropic: e.g. a thin film is inherently different along the film normal than in the in-plane direction, and thus is not truly anisotropic.

Anisotropy in the sample is reflected in anisotropy in the [[reciprocal-space]]. Thus, the [[scattering]] pattern one observes on the detector will depend on the orientation of the sample with respect to the beam.

==Reciprocal-space==
This is best understood in terms of [[reciprocal-space]]. Recall that the signal observed on the detector arises from the intersection of the [[Ewald sphere]] with the reciprocal lattice.

[[Image:R000.png|450px|thumb|center|Simplified 2D representation of a scattering experiment. The reciprocal-space of a crystal (blue), contains an array of peaks. The only peaks that are observed on the detector are those that intersect the Ewald sphere.]]

If we reorient the sample, we bring a different set of reciprocal-space peaks into the intersection condition. That is, we bring a different set of crystal planes in the sample into the 'Bragg condition' wherein they give rise to a diffraction peak.

[[Image:R020.png|450px|thumb|center|A different sample orientation brings a different set of peaks onto the detector.]]

==Reconstruction==
In order to map out the entire reciprocal-space, one can completely rotate the sample, and collection a wide set of images. Adding these images together enables the full 3D reciprocal-space to be reconstructed.

[[Image:crystallography_anim.gif]]

← Older revision		Revision as of 15:41, 8 July 2019
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	* [[Reciprocal-space mapping]]		* [[Reciprocal-space mapping]]
	* [[Example:P3HT orientation analysis]]		* [[Example:P3HT orientation analysis]]
		+	* L. Urzhumtseva and A. Urzhumtsev [http://scripts.iucr.org/cgi-bin/paper?gj5227 py_convrot: rotation conventions, to understand and to apply] ''J. Appl. Cryst.'' '''2019''' [https://doi.org/10.1107/S1600576719007313 doi: 10.1107/S1600576719007313]

@@ Line 20: / Line 20: @@
 ==See Also==
 * [[Rocking scan]]
 * [[Example:P3HT orientation analysis]]

← Older revision		Revision as of 21:22, 12 January 2015
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	==Reconstruction==		==Reconstruction==
−	In order to map out the entire reciprocal-space, one can completely rotate the sample, and collection a wide set of images. Adding these images together enables the full 3D reciprocal-space to be reconstructed.	+	In order to [[reciprocal-space mapping\|map out the entire reciprocal-space]], one can completely rotate the sample, and collection a wide set of images. Adding these images together enables the full 3D reciprocal-space to be reconstructed.

← Older revision		Revision as of 13:27, 3 November 2014
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	==See Also==		==See Also==
	* [[Rocking scan]]		* [[Rocking scan]]
		+	* [[Example:P3HT orientation analysis]]

← Older revision		Revision as of 02:04, 30 September 2014
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	[[Image:crystallography_anim.gif]]		[[Image:crystallography_anim.gif]]
		+
		+	==See Also==
		+	* [[Rocking scan]]

@@ Line 8: / Line 8: @@
 [[Image:R000.png|450px|thumb|center|Simplified 2D representation of a scattering experiment. The reciprocal-space of a crystal (blue), contains an array of peaks. The only peaks that are observed on the detector are those that intersect the Ewald sphere.]]
-If we reorient the sample, we bring a different set of reciprocal-space peaks into the intersection condition. That is, we bring a different set of crystal planes in the sample into the 'Bragg condition' wherein they give rise to a diffraction peak.
+If we reorient the sample, we bring a different set of reciprocal-space peaks into the intersection condition. That is, we bring a different set of crystal planes in the sample into the '[[Bragg's law|Bragg condition]]' wherein they give rise to a [[diffraction]] peak.
 [[Image:R020.png|450px|thumb|center|A different sample orientation brings a different set of peaks onto the detector.]]

@@ Line 1: / Line 1: @@
 For isotropic materials, the orientation of the sample with respect to the beam does not matter. However, for any sample that is anisotropic the '''sample orientation''' will strongly influence the scattering pattern. This effect is relevant for any intrinsically anisotropic material, including crystals and aligned bulk materials (liquid crystals, stretched polymers, etc.). Any material which has broken symmetry will also be anisotropic: e.g. a thin film is inherently different along the film normal than in the in-plane direction, and thus is not truly anisotropic.
-Anisotropy in the sample is reflected in anisotropy in the [[reciprocal-space]]. Thus, the [[scattering]] pattern one observes on the detector will depend on the orientation of the sample with respect to the beam.
+Anisotropy in the sample is reflected in anisotropy in the [[reciprocal-space]]. Thus, the [[scattering]] pattern one observes on the [[detector]] will depend on the orientation of the sample with respect to the beam.
 ==Reciprocal-space==