Small-angle X-ray scattering - Hasylab - Desy
Small-angle X-ray scattering - Hasylab - Desy
Small-angle X-ray scattering - Hasylab - Desy
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Intensity (arbitrary units)<br />
10 12<br />
10 10<br />
10 8<br />
10 6<br />
10 4<br />
10 -1<br />
Fractals, self similar objects<br />
q (1/nm)<br />
Sphere (projected)<br />
Circle in 2d<br />
q -4<br />
q -3<br />
d e = 2!<br />
D m = mass fractal dimension<br />
D s = surface fractal dimension<br />
d e = Euclidian dimension (3 in real life)<br />
10 0<br />
Many SAXS curves follow a power law<br />
I(q) ∝ q -α<br />
Mass fractal:<br />
α = Dm (0 − 3)<br />
Surface fractal:<br />
α = 2d e –D s (6 − D s , when d e = 3)<br />
Shape D m D s<br />
Line 1 0<br />
Platelet 2 1<br />
Sphere 3 2<br />
Porod law<br />
I(q) ∝ q -4
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