Scattering features
Scattering experiments (x-ray or neutron) generates images which can be thought of as the Fourier transform of the material's realspace structure. I.e. the image is a slice through a conceptual 3D reciprocal-space. Although a scattering pattern can be arbitrarily complex, there are usually various features that can be analyzed separately, and from which one can learn much about a sample's structure. In particular, samples with well-defined structural order give rise to distinct scattering features, such as sharp rings or even distinct spots on the area detector image.
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Rings
TBD
Spots
TBD
Diffuse Scattering
Many samples will exhibit diffuse scattering: scattering intensity over a broad range of angles, without a distinct peak or maximum. This kind of scattering usually comes from disorder within the sample. For instance, low-q diffuse scattering can come from nanoscale or microscale porosity, or from surface roughness in GISAXS. High-q diffuse scattering can arise from the defects in atomic lattices (and from the thermal motion of atoms in a lattice). Although one can generally assign diffuse scattering to some kind of disorder, it is difficult to make an unambiguous link, because there are many effects that can generate diffuse scattering.
