Getting large - What's the difference between SAXS and USAXS?


Small-angle X-ray scattering (SAXS) is an analytical method to determine the size and structure of nanoscale systems, e. g. particle dispersions or porous materials. It relies on the elastic scattering of X-ray photons on the sample. This results in a scattering pattern that can be evaluated at small angles (typically <0.1° 2θ to about 10° 2θ) to obtain information on the nanoscopic structure of the analyzed sample. The scattering signal is very close to the intense primary beam. As a consequence, to measure smaller and smaller angles the beam must be collimated to a very narrow size. This way, modern SAXS systems can measure scattering angles as low as 0.015 2θ. However, there are practical limits to how much further the beam can be collimated in order to still obtain data in a reasonable amount of measurement time. Assuming Copper Ka radiation, a scattering angle of 0.015 2θ roughly relates to 300 nm particle diameter in real space, which defines the maximum size limit of structures that can be measured by this method.
To measure larger structures, ultra-small angle X-ray scattering (USAXS) can be used. This no longer relies on collimating the X-ray beam. Instead, it uses a set of crystals to effectively decrease the beam divergence to much smaller values. This can be done by using a slit system allowing extension of the maximum size limit to the order of several micrometers.
This webinar will discuss the benefits and downsides of both methods.

Webinar content:

  • Description of the term “resolution” in SAXS
  • Differences between SAXS and USAXS
  • Selected application examples of both SAXS and USAXS

Target group:

  • Beginners in small-angle X-ray scattering
  • Anyone interested in the characterization of nanostructured materials
Language: English
Trainer: Dr. Andreas Keilbach
Andreas Keilbach

Dr. Andreas Keilbach obtained his PhD in Physical Chemistry from the University of Munich, with a focus in porous materials. After his PhD studies, he joined Anton Paar in April 2011 and is currently part product manager for small-angle X-ray scattering at Anton Paar GmbH.


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