Laue Diffraction

1
Laue Diffraction
Laue diffraction of NaCl taken with radiation
from a tungsten-target tube operated at 60 kV.
The dark patch below the center disk was caused
by scattered x-rays. To prevent overexposure, a
lead disk masked the center for all but the last
second of a 40 minute exposure.
2
Bragg Reflection
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q
a
c
e
a
b
d
q
a
e
a
d
c
b
3
X-Ray Spectrum
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6
Characteristic radiation
Ka
5
4
25 kV
Continuous radiation or bremsstrahlung
3
X-ray intensity (arb. units)
Kb
20 kV
2
15 kV
1
10 kV
lmin
5 kV
0
0.0
1.0
2.0
3.0
l in Å
4
Hypothetical Energy Level Diagram
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5
Absorption of X-rays
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To MI edge
5000
LI
LIII
LII
4000
x 10
3000
Linear absorption coefficient (cm-1)
K
2000
1000
0
0.6
1.2
0.4
0.8
1.0
1.4
Å
1.6
0.2
lK
Wavelength l
keV
10
8
9
20
30
?
15
50
100
X-ray energy
6
X-ray Absorption
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7
Auger Process
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8
Quantum Nature of Emission/Absorption
VII VI V IV III II I
N
V IV III II I
M
Energy (log scale)
III II I
L
h
b
l
g
b
g
b
a
LII
LIII
LI
K
a2
b3
b1
g2
g1
a1