motor driven incident slits (define the incident x-ray beam size) synchrotron x-ray upstream beam...
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Motor driven incident slits(define the incident x-ray
beam size)
Synchrotron x-ray
upstreambeam aperture
CCD camera Video camera
Long working distance microscope (10X)
2nd mirror
fluorescent screen (YAG crystal) and reflection mirror
sample cell assembly and cubic anvil press (DIA)
double crystal monochromator
SSD/CCD detector
Symmetry
N
360
Rotation Inversion Mirror reflection TranslationSymmetry operation
Symmetry element Rotation axis Center of inversion Mirror plane Vector
Other (complex) symmetry elements
Rotation Inversion Reflection Translation
Rotation --- Roto-inversion axis xxx Screw axis
Inversion --- --- xxx xxx
Reflection --- --- --- Glide plane
Translation --- --- --- ---
Classification of symmetry elements 1
Proper symmetry elements improper symmetry elements
Rotation axis Inversion center
Translation axis Reflection plane
Screw axis Inversion axis
Glide plane
(do not change shape) (involve shape change)
Classification of symmetry elements 2
Finite symmetry elements Infinite symmetry elements
Rotation axis Translation axis
Inversion center Screw axis
Reflection plane Glide plane
Inversion axis
(Result in finite number of objects) (Result in infinite number of objects)
Finite symmetry operations
Crystallographic Rotation axis
N = 1, 2, 3, 4, 5, 6, 7…
N
360
Homework3: (due on Oct. 31)
Assuming the following facilities are available:
A. sealed x-ray tube source, curved position sensitive detector, radius 150 mm.
B. sealed x-ray tube source, Bragg-Brentano goniometer, radius 200 mm, scintillation detector.
C. rotating anode source, Bragg-Brentano goniometer, radius 285 mm, scintillation detector.
D. sealed x-ray tube source, Bragg-Brentano goniometer, radius 250 mm, cooled solid state detector.
E. Synchrotron x-ray facility, Bragg-Brentano goniometer, radius 100 to 500 mm, cooled solid state detector.
1.If you are to collect powder diffraction data with high resolution, what is the order of these five facilities should you choose?
2.If you have 20 different samples to identify using x-ray diffraction and each facility charges you base on the time used, which facility should you choose (excluding synchrotron facility)?