X-Ray Measurement Methods From Chapter 6 of Textbook 2 and other references

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X-Ray Measurement Methods From Chapter 6 of Textbook 2 and other references. http://www.stanford.edu/group/glam/xlab/MatSci162_172/LectureNotes/06_Geometry,%20Detectors.pdf. Diffractometer Hull/Debye- Scherrer method Pinhole method Laue Method Rotating Crystal Method.

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## X-Ray Measurement Methods From Chapter 6 of Textbook 2 and other references

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X-Ray Measurement Methods

From Chapter 6 of Textbook 2 and other references

http://www.stanford.edu/group/glam/xlab/MatSci162_172/LectureNotes/06_Geometry,%20Detectors.pdf

Diffractometer

Hull/Debye-Scherrer method

Pinhole method

Laue Method

Rotating Crystal Method

Schematics of a typical X-ray diffractometer:

S: source; C: specimen; H: goniometer; O: rotation axis;

A, B: slits for collimation; F: slit; G: detector;

E and H can be mechanically; coupled  2 and  relation;

focusing monochromator

CM= 2R, OC = R

Cut off the crystal behind the

dotted line to a radius R

http://cheiron2008.spring8.or.jp/lec_text/Sep.30/2008_T.Matsushita_1.pdfhttp://cheiron2008.spring8.or.jp/lec_text/Sep.30/2008_T.Matsushita_1.pdf

http://cheiron2008.spring8.or.jp/lec_text/Sep.30/2008_T.Matsushita_1.pdfhttp://cheiron2008.spring8.or.jp/lec_text/Sep.30/2008_T.Matsushita_1.pdf

X-ray Optics:

According to Euclid: “the angles in the same segment of a circle are equal to one another” and “the angle at the center of a circle is double that of the angle at the circumference on the same base, that is, on the same arc”.

Bragg-Brentano diffractometers

Parallel beam geometry in Debye-Scherrer mode using a double monochromator (DM) and an analyzer crystal

Single crystal

Polycrystal

An ideal powder sample

many crystallites in random orientations; smooth and

constant distribution of orientations; Crystallites < 10 μm

Sample preparation:

There are many methods of preparing samples:

– Sample should normally be ground to < 10 μm

– Sample may be sieved to avoid large or small

crystallites

– Sample may be loaded into a holder by pressing from

the back while using a slightly rough surface at the

front

– Sample may be pressed in from the front

– Sample may be mixed with a binder (epoxy or similar

material) and then cut and polished to give a suitable

surface

Hull/Debye-Scherrermethod:

Film

Film

2=S/R

S

2

2

S

R

Film

Film

hole

S

S

2

S

S

R

hole

2

2

2

2

2S

Film

hole

S

2

R

2

2

2

and

Resolving

power

http://www.stanford.edu/group/glam/xlab/MatSci162_172/LectureNotes/06_Geometry,%20Detectors.pdfhttp://www.stanford.edu/group/glam/xlab/MatSci162_172/LectureNotes/06_Geometry,%20Detectors.pdf

Pinhole photographs

D

D

F

F

Incident

X-Ray

2q

A

C

A

r1

C

r2

S

B

B

180o-2q

tan2q = r1/D

tan(180o-2q) = r2/D

monochromatic or white radiation and powder sample

Laue methode: white radiation and single crystal

Rotating Crystal Method

http://202.141.40.218/wiki/index.php/Unit-2:_Introduction_to_X-ray_diffraction

Wavelength: incident beam = diffracted beam

Magnitude of k the same = 1/.

Diffraction condition: k = G

k = G

k = G

2B

2B

Diffraction Methods:

Method 

Laue Variable fixed

Rotating crystal Fixed Variable

Powder Fixed Variable

vaied 

reciprocal lattice isrotated or Ewald

sphere is rotated