Scattering intensity

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The scattering intensity is the amount of radiation (e.g. x-ray or neutron) scattered at any particular angle. This quantity is usually given by \scriptstyle I(q), where q is the momentum transfer (a vector in reciprocal-space).

Contributions

The scattering intensity is frequently divided into the contribution from the form factor (F or P) and structure factor (S):


\begin{alignat}{2}
I(q) & = \langle |F(\mathbf{q})|^2 S(\mathbf{q}) \rangle \\
 & = P(q) \left\langle \frac{|F(\mathbf{q})|^2}{P(q)} S(\mathbf{q}) \right\rangle \\
 & = P(q)S(q)
\end{alignat}

The form factor describes the shape of scattering objects, whereas the structure factor describes the organization of these objects (disordered, in a lattice, etc.). The scattering intensity, \scriptstyle I(q), is what is measured experimentally on a detector (including a possible background). However, this quantify is frequently converted into (or treated as), \scriptstyle P(q) or \scriptstyle S(q), in order to perform further analysis.

See Also