X- ray scattering exam: making science to look cool

1. X-RAY SCATTERINGFROM ATOMS TO COMPLEX SYSTEMS
Giulio Ungaretti
-EXPERIMENTAL X-RAY PHYSICS EXAM -19/7/2013
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2. Outline
•Simple models
•Adding complexities
•Real life examples
Slides and blackboard
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3. Atomic scattering
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f0
(Q) =
Z
⇢(r)iQ·r
d3
r
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4. Molecular scattering
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fmol
(Q) =
X
j
fj(r)eiQ·rj
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5. Molecular scattering II
and, more generally:
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ISAXS
(Q) / ⇢2
P(Q)S(Q)even more:
ISAXS
(Q) / ⇢2
P(Q)
I(Q) = Nf(Q)2
+ f(Q)2
X
n
Z
V ol
(⇢(rn rm) ⇢average)eiQ·(rn rm
)dV +
| {z }
short range
+ f(Q)2
X
n
Z
V ol
⇢averageeiQ·(rn rm)
dV
| {z }
SAXS
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6. Adding complexities
• Poly disperse systems
• Complex structures
• Dynamical diffraction
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7. Real life examples I:
kr scattering
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8. Real life examples II:
CF4 molecule
Unexpected
attenuation !!!!!! explian
alluminum shit
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9. Real life examples III:
SAXS(ish)-milk fat
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10. Real life examples III:
WAXS milk fat
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11. Conclusions
•Powerful structural tool
•Can use simple models
•Versatile method
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