The difference between SAXS and WAXS

SAXS is used to analyze nanosized particles and domains (size range: 1 to 100 nm) which scatter towards small angles. The SAXS pattern provides information on the size and shape of these particles. It therefore helps to elucidate the nanostructure of the sample.


WAXS/XRD is used to analyze smaller structures (<1 nm). Atoms and interatomic distances scatter towards large angles. The obtained Wide-Angle X-ray Scattering (WAXS) pattern provides information on the phase state, crystal symmetry and the molecular structure.

SAXS

Small-angle X-ray Scattering is a non-destructive method which evaluates the X-ray scattering pattern of nanoparticles (homogeneous particles, macromolecules, etc.) at small angles to get information about their particle structure. The incoming X-ray beam interacts with the electrons of all atoms in the macromolecule, resulting in a so-called “scattering pattern” (= different X-ray intensities at different scattering angles), which is characteristic for the particle structure, i.e. size, shape and internal structure.

SAXS parameters

SAXS is used to determine several parameters of nanostructured samples:

• Shape,
  
• Size,
• Internal Structure, 
• Crystallinity,
  
• Porosity (Surface per volume).

Scattering vector q

It is common practice in small-angle scattering (SAXS, SANS, SALS) to present scattering angles in q: instead of the scattering angle 2Theta which is normally used in XRD. This provides the benefit of obtaining results independent of the wavelength. q (kursiv) is also known as momentum transfer.