Small Angle X-ray Scattering is a non-destructive and highly versatile standard method to study at the nanoscale the structure of any type of material ranging from innovative nanostructured materials to biological macromolecules. With this technique, the in- homogeneities of the electron density in the samples are characterized, as a function of the scattering angle.
The investigated sample is irradiated with a monochromatic radiation, and scattered X-rays are typically collected in an angular range of 0 – 10° by a suitable detector (ie. CCD or imaging plate) and up to 60° (by using an imaging plate for the systems coupling SAXS and Wide Angle X-Ray Scattering, WAXS). By means of appropriate model fittings and reconstructions, SAXS data deliver information on averaged particle sizes, shapes, distributions and materials' porosity.
SAXS allows structural studies in a dimension range typically between 1 and 100 nm; the dimension limits depend on the selected instrument. Samples can be probed in solution, solid, at the interface or in the gas phase; with specially designed sample holders, they can be measured under various conditions, like at different temperature, humidity, high pressure and under mechanical stress/strain conditions. Moreover, SAXS can be used for time-resolved studies on fast structural transitions during chemical reactions or self-assembly process.
Grazing-incidence (GISAXS) measurements can be performed to study self-assembly processes on surfaces, as well as to perform structural characterisations of thin films.
At wider scattering angle (Wide Angle X-ray Scattering, WAXS), intramolecular dimensions, as well as the degree of crystallinity of the samples, can be probed.