Xray sources Sealed tubes Coolidge type common Cu

X-ray sources Sealed tubes - Coolidge type common - Cu, Mo, Fe, Cr, W, Ag intensity limited by cooling req'ments (2 -2. 5 k. W)

X-ray sources Sealed tubes - Coolidge type common - Cu, Mo, Fe, Cr, W, Ag intensity limited by cooling req'ments (2 -2. 5 k. W) Intensity also changes w/ take-off angle

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

X-ray sources

X-ray sources Rotating anode high power - 40 k. W demountable various anode types

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

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)

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

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

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

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

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

Beam conditioning Collimation

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.

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.

Beam conditioning Monochromatization Crystal monochromators – Li. F, Si. O 2, pyrolytic graphite critical – reflectivity ex: for Mo. K , Li. F 9. 4% graphite 54 %

Beam conditioning Monochromatization Crystal monochromators – Li. F, Si. O 2, pyrolytic graphite critical – reflectivity ex: for Mo. K , Li. F 9. 4% graphite 54 % resolution – determines peak/bkgrd ratio & spectral purity best - Si – 10" graphite – 0. 52°

Beam conditioning Monochromatization Monochromator shape usually flat – problems w/ divergent beams concentrating type – increases I by factor of 1. 5 -2

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

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

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

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)