<unk><unk><unk>  (SAS) of<unk> -rays (SAXS) and neutrons (SANS) is a fundamental method for structure analysis of materials. SAXS allows one to study the structure of a variety of objects such as solutions of<unk>  macromolecules, nanocomposites, alloys, synthetic polymers, etc. SAXS is an analogous method to<unk> -ray diffraction and wide<unk> <unk> -ray<unk> , but in addition SAXS yields information on the sizes and shapes of non-crystalline particles.
SAXS patterns are collected at very<unk><unk> s (less than a degree). SAXS is capable of delivering structural information of macromolecules between 1 and 25 nm, of repeat distances in partially ordered systems of up to 150 nm. Ultra<unk><unk> <unk> -ray<unk>  (USAXS) can resolve even larger dimensions. The grazing incidence<unk><unk> <unk> -ray<unk>  (GISAXS) is a very powerful technique for studying the surface and interface problems.
Usually SAXS is used to determine the structure of particle systems in terms of average particle sizes and shapes. The materials can be solid or liquid and they can contain solid, liquid or gaseous domains (so-called particles) of the same or another material in combination. The method is accurate, non-destructive and usually requires only a minimum of sample preparation. Applications are very broad and include colloids of all type, metals, cement, oil, polymers, plastics, proteins, foods and pharmaceuticals and can be found in research as well as in quality control. Furthermore the method allows to determine parameters, e.g., inner structure and surface-to-volume ratio.
Conceptually, SAXS experiment is simple: the sample is exposed to<unk> -rays and the<unk>  radiation is registered by a detector. As the SAXS measurements are done very close to the primary beam <unk><unk> s"), the technique profits immensely from the brilliance of<unk> -ray photon beams provided by synchrotron storage rings. The<unk> -ray<unk>  curve (intensity versus<unk> <unk>  is used to create a low-resolution model of a protein, shown on the right picture. One can further use the<unk> -ray<unk>  data and fit separate domains <unk> -ray or NMR structures)  into „SAXS envelope“.
In comparison to other structure determination methods, like NMR or<unk> -ray crystallography, SAXS allows one to overcome some restraints. For example, NMR is limited to protein size, whereas SAXS can be used for<unk>  molecules as well as for large multimolecular assemblies. Structure determination by<unk> -ray may take several weeks or even years, whereas SAXS measurements take days.
Biological small-angle X-ray scattering
Spectrophotometry
Protein nuclear magnetic resonance spectroscopy
Ion chromatography
Enzyme assay
Gas diffusion method
Infrared spectroscopy
Near infrared spectroscopy