Powder Diffraction - Spallation Neutron Source
Powder Diffraction - Spallation Neutron Source
Powder Diffraction - Spallation Neutron Source
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Coherent Atomic Scattering Power (diffraction)<br />
Structure factors: F hkl = n f i exp[2i(hx i + ky i + lz i)] exp(-U iQ 2 /2)<br />
<strong>Diffraction</strong> Intensity: I hkl |F hkl| 2<br />
X-rays: The scattering power (form<br />
factor, f i) of an atom depends on the<br />
number of electrons in the atom and<br />
Q (Qsin/)<br />
<strong>Neutron</strong>s: The scattering power<br />
(scattering length, b i) of an atom<br />
depends on the isotope and is<br />
independent of Q<br />
– A few isotopes scatter with opposite<br />
phase to most, for these we write f (b)<br />
as negative<br />
– Magnetic scattering is from electrons;<br />
f M(Q) similar to x-rays<br />
Q or sin/, Å -1<br />
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