MENA3100, 3/2-10, OBK

1. MENA3100, 3/2-10, OBK X-ray diffraction XRD Røntgendiffraksjon Single crystal Powder

2. Diffraction

4. Crystal Atomic arrangement Lattice

5. Lattice + base The 14 Bravais lattices 1848

7. Bragg’s law 2d sinq = nl

8. Bragg’s law 2d sinq = nl n = 2 2nd. order But XRD is typically done with monochromatic radiation

9. Bragg’s law 2d sinq = nl 2nd. order from 001 1th. order from 002

10. The 14 Bravais lattices Face centered cubic lattice g-iron NaCl g-brass

11. Extinction Utslukning Example: Face centered cubic Special example: Cubic close packed structure

12. Extinction Utslukning Example: Face centered cubic Special example: Cubic close packed structure

13. Don’t confuse with ...

14. X-ray diffraction Need X-rays Wavelenght CuKa1 = 1.54056 Å MoKa1 = 0.70930 Å Characteristic X-rays CuKa1 = 1.54056 Å CuKa2 = 1.54433 Å Brehmsstrahlung = white radiation I(CuKa1) = 2·I(CuKa2) CuKa = 1.5418 Å

15. Need sample Single crystal Powder

16. Need experimental setup Bragg-Brentano geometry (Primary monochromator) Diffractometer (Secondary monochromator)

17. Characteristic X-rays Brehmsstrahlung = white radiation Want monochromatic radiation Monochromators: Many possibilities

18. Euclid, The Elements (300 B.C.) Proposition 21, Book III: The angles in the same segment of a circle are equal to another Johansson monochromator

19. Bragg-Brentano geometry The source S can be:

20. Need detector … Need some slits … Fixed slits: Smaler area at high angle  Smaller area at high angles Variable slits: Same area at all angles S Sample

22. The experiment Got some crystals Want a powder Gets lot of small crystals

24. Want powder Random orientation

25. The result The diffractogram Quartz (Don’t call it spectrum)

26. Why?

27. Identification PDF = JCPDS

28. Indexing

29. Lattice dimensions

31. Strain Particle size

32. Fluorescens

33. CuKa1 = 1.54056 Å CuKa2 = 1.54433 Å Primary and secondary monochromators

34. Rietveld refinement