Small Angle X-ray Scattering (SAXS)

Small angle X-ray Scattering (SAXS) is a nondestructive technique for characterization of the size and shape of nanoparticles and large molecules, pore sizes, and characteristic distances of partially ordered materials.

How SAXS works – a monochromatic X-ray beam illuminates the sample and X-rays that are elastically scattered at angles close to the incident beam (0.1 – 10 degrees) are detected. The scattering signal is the difference between the average electron densities of the macromolecules and the solvent.

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Instrumentation Available

Key Attributes

  • Signal Detected: Scattered X-rays, scattering angle range 0.1 – 10°
  • Elements Detected: All if they are present
  • Can provide structural information on dimensions of 1 – 100 nm
  • Can measure repeat distances in partially ordered systems of up to 150 nm

Strengths

  • Nondestructive
  • Crystalline samples not needed
  • Performs quantitative measurements of particle shapes and sizes
  • Minimal/no sample preparation
  • No vacuum required

Limitations

  • Aggregation of molecules will bias the results
  • Resolution of 1 – 3 nm
  • Data must be spatially averaged

Applications

  • Characterization of conformational changes in macromolecules
  • Information of macromolecular folding and unfolding
  • Characterization of lipid vesicle dispersions

 

Additional Reading