Small Angle Scattering of neutrons and xrays - NeutronXraySchool ...
Small Angle Scattering of neutrons and xrays - NeutronXraySchool ...
Small Angle Scattering of neutrons and xrays - NeutronXraySchool ...
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Analysis <strong>of</strong> SAS data<br />
here typical particulate solution scattering<br />
= Δρ2 n V2 dΣ<br />
(q ) Δρ n V P(q) S(q)<br />
ddΩ<br />
Ω<br />
lim q,n → 0:<br />
dΣ<br />
( q =<br />
dΩ<br />
0)<br />
= Δρ 2 nV 2<br />
• n - Number density<br />
(concentration)<br />
• V - PParticle ti l volume l<br />
(molecular mass)<br />
• Δρ2 - Contrast = square <strong>of</strong><br />
scattering length density<br />
diff difference bbetween t particle ti l <strong>and</strong> d<br />
medium<br />
– x-rays: electron density<br />
– <strong>neutrons</strong>: isotope labeling,<br />
particularly H > D<br />
• P( P(q) ) - Si Size & shape h<br />
• S(q) - Interaction<br />
Measure <strong>and</strong> subtract background very carefully!<br />
Do the absolute calibration – it’s worth the effort!
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