What is transmission small angle X-ray scattering (TSAXS)?

TSAXS refers to SAXS experiments performed in transmission mode, which is the conventional way of doing these experiments, so TSAXS and SAXS are essentially the same thing. The term TSAXS is used to distinguish it from other geometries, such as GISAXS.

Small-angle X-ray scattering (SAXS) is diffuse scattering caused by the electron density distribution, which appears at scattering angles of approximately 5° or less. Since the diffuse scattering pattern varies depending on particle size and particle size distribution (whether or not the particle size is uniform), nanoscale structural information can be obtained by analyzing it. SAXS instruments are equipped with an optical system that allows precise measurement of small scattering angle regions. The particle sizes that can be evaluated by SAXS range from several nm to several hundred nm, and samples in various states, such as particle dispersion solutions and powders, can be analyzed. The high penetrating power of X-rays also makes it possible to evaluate particles dispersed in solids.There are several methods to analyze particle size distribution, but SAXS is attracting attention as a non-destructive measurement method that can be performed under atmospheric pressure.

SAXS is a powerful tool for studying nanoscale structures and is used in a wide range of fields, including liquid crystals, metals, biological materials, and soft matter such as polymers. The particle size distribution of powder and filler in polymers can be evaluated by SAXS. The periodic structure of the lamellar structure, in which the polymer chains of crystalline polymers are regularly folded, can also be evaluated. This information is known to relate to material properties and performance. For example, it has been reported that the dielectric constant of BaTiO₃, a typical ferroelectric material, increases with decreasing particle size and loses ferroelectricity below a certain critical size. Thus, it is important to evaluate the nanoscale structure in the R&D and quality control stages.