X-RAY SCATTERINGFROM ATOMS TO COMPLEX SYSTEMS

Giulio Ungaretti-EXPERIMENTAL X-RAY PHYSICS EXAM -19/7/2013

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Outline

• Simple models

• Adding complexities

• Real life examples

Slides and blackboard

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Atomic scattering

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f 0(Q) =

Z⇢(r)iQ·rd3r

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Molecular scattering

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f

mol(Q) =X

j

f

j

(r)eiQ·rj

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Molecular scattering II

and, more generally:

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ISAXS(Q) / �⇢2P (Q)S(Q)even more:

ISAXS(Q) / �⇢2P (Q)

I(Q) = Nf(Q)2 + f(Q)2X

n

Z

V ol

(⇢(rn

� rm

)� ⇢average

)eiQ·(rn�rm)dV +

| {z }short range

+ f(Q)2X

n

Z

V ol

⇢average

eiQ·(rn�rm)dV

| {z }SAXS

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Adding complexities

• Poly disperse systems• Complex structures• Dynamical diffraction

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Real life examples I: kr scattering

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Real life examples II: CF4 molecule

Unexpected attenuation !!!!!! explian alluminum shit

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Real life examples III: SAXS(ish)-milk fat

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Real life examples III: WAXS milk fat

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Conclusions

• Powerful structural tool

• Can use simple models

• Versatile method

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