SAXS and WAXS, two complementary measurements
SAXS (small-angle X-ray scattering) and WAXS (wide-angle X-ray scattering) are often measured together on a synchrotron beamline.
- SAXS: probes structures from about a nanometre to a few hundred nanometres (nanoparticle size and shape, polymers, pores).
- WAXS: probes atomic-scale organisation (crystalline phases, lattice parameters, orientation).
The difference lies in the scattering angle: the larger the structure, the closer to the beam its signal appears. For the mechanical engineer, this means requirements on the sample-to-detector distance, sample positioning and beam path, often under vacuum to limit scattering by air.
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