X-ray sources

1. X-ray sources Sealed tubes - Coolidge type common - Cu, Mo, Fe, Cr, W, Ag intensity limited by cooling req'ments (2-2.5kW)

2. X-ray sources Sealed tubes - Coolidge type common - Cu, Mo, Fe, Cr, W, Ag intensity limited by cooling req'ments (2-2.5kW) Intensity also changes w/ take-off angle

3. X-ray sources Intensity also changes w/ take-off angle But resolution decreases w/ take-off angle

4. X-ray sources

5. X-ray sources Rotating anode high power - 40 kW demountable various anode types

6. X-ray sources Synchrotron need electron or positron beam orbiting in a ring beam is bent by magnetic field x-ray emission at bend

7. X-ray sources Synchrotron need electron or positron beam orbiting in a ring beam is bent by magnetic field x-ray emission at bend Advantages 10-4 - 10-5 rad divergence (3-5 mm @ 4 m)

8. X-ray sources Synchrotron need electron or positron beam orbiting in a ring beam is bent by magnetic field x-ray emission at bend Advantages 10-4 - 10-5 rad divergence (3-5 mm @ 4 m) high brilliance wavelength tunable

9. X-ray sources Synchrotron Advantages 10-4 - 10-5 rad divergence (3-5 mm @ 4 m) high brilliance wavelength tunable

10. X-ray sources Synchrotron Advantages 10-4 - 10-5 rad divergence (3-5 mm @ 4 m) high brilliance wavelength tunable

11. X-ray sources Synchrotron Advantages 10-4 - 10-5 rad divergence (3-5 mm @ 4 m) high brilliance wavelength tunable

12. X-ray sources Synchrotron need electron or positron beam orbiting in a ring beam is bent by magnetic field x-ray emission at bend Advantages 10-4 - 10-5 rad divergence (3-5 mm @ 4 m) high brilliance wavelength tunable high signal/noise ratio

13. Beam conditioning Collimation

14. Beam conditioning Monochromatization -filters – matls have at. nos. 1 or 2 less than anode 50-60% beam attenuation placing after specimen/before detector suppresses sample fluorescence allows passage of high intensity & long wavelength white rad.

15. Beam conditioning Monochromatization -filters – matls have at. nos. 1 or 2 less than anode 50-60% beam attenuation placing after specimen/before detector suppresses sample fluorescence allows passage of high intensity & long wavelength white rad.

16. Beam conditioning Monochromatization Crystal monochromators – LiF, SiO2, pyrolytic graphite critical – reflectivity ex: for MoK, LiF 9.4% graphite 54 %

17. Beam conditioning Monochromatization Crystal monochromators – LiF, SiO2, pyrolytic graphite critical – reflectivity ex: for MoK, LiF 9.4% graphite 54 % resolution – determines peak/bkgrd ratio & spectral purity best - Si – 10" graphite – 0.52°

18. Beam conditioning Monochromatization Monochromator shape usually flat – problems w/ divergent beams concentrating type – increases I by factor of 1.5-2

19. Beam conditioning Monochromatization Monochromator shape focusing monochromators elastically or plastically bend crystal

20. Beam conditioning Monochromatization Monochromator shape focusing monochromators elastically or plastically bend crystal Johann geometry radius of curvature = 2R R = radius of instrument focusing circle

21. Beam conditioning Monochromatization Monochromator shape focusing monochromators elastically or plastically bend crystal Johansson geometry bend radius = 2R ground radius = R

22. Beam conditioning • Mirrors • total reflection below critical angle • polished Al or optical glass • curved mirrors collimate, can even focus beam • (high peak to bkgrd ratio)