Small and Wide-Angle X-ray Scattering (SAXS and WAXS) are analytical techniques used to study the structure and interactions of materials in the 1 to ~300 nm range. Using USAXS (Ultra SAXS) this range can be extended to over a micron. With these closely related techniques, information can be gained on particle sizes and shapes, order an orientation, particle interactions and internal structures. Measurements can either be done on bulk materials, or on the surface only when using GISAXS or GIWAXS (Grazing Incidence SAXS or WAXS).
The materials typically studied include polymers, metals, colloids, liquid crystals and biological samples e.g. proteins and RNA/DNA (also referred to as Bio-SAXS). Bio-SAXS has recently gained significant interest in research as well as industry. It has proven to be a valuable technique for the investigation of flexible and disordered proteins and it is complementary to high resolution techniques such as Protein Crystallography and Electron Microscopy.
SAXS measurements can be done on many different types of samples: gels, liquids, solids, etc. Furthermore, little or no sample preparation is required. These two characteristics enable measurements in the native state and in-situ measurements. This gives invaluable insight into the behavior of the analytes in real-life conditions.
In general, the scattered signal is recorded at diffraction angles below 6° and the sample is positioned at a long distance from the detector. This means that the scattered signal is often weak. Therefore, SAXS measurements benefit greatly from the use of a high brilliance X-ray source such as the Excillum MetalJet. Higher signal means that the weak scattering effects become stronger, more visible and thus more readily studied. Especially time dependent studies (such as the kinetics of particle formation), in-situ measurements (for example under tensile or shear stress) and measurements on weak scatterers like most proteins, benefit hugely from the MetalJet’s high brilliance. Moreover, the use of a high brilliant source reduces the measurement time hereby increasing the amount of measurements that can be done.