Small angle scattering

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Small angle scattering or diffraction, ( KWS , engl. Small-angle scattering , SAS ) is a physical measurement technique for the investigation of structures whose dimensions are relatively large compared to the wavelength of the radiation used. Either X-rays ( small-angle x-ray scattering , SAXS ) or neutron radiation ( SANS ) are diffracted .

Basics

With elastic scattering, the scattering vector has the amount

where is the wavelength of the radiation used and the scattering angle between the incident and the specifically considered diffracted beam. The incident wavelength is typically of a similar order of magnitude as in regular X-ray or neutron diffraction , i.e. a few angstroms , comparable between atomic distances. For small angles (from approximately to several orders of magnitude below), q also becomes very small and thus enables the investigation of relatively large structures. On this scale, the examined medium can be described in a continuum approximation by a scattering length - density function .

variants

A variant of the small-angle scattering is the small-angle scattering with grazing incidence .

literature

  • LA Feigin, DI Svergun: Structure Analysis by Small-Angle X-Ray and Neutron Scattering . Springer Science & Business Media, 2013, ISBN 978-1-4757-6624-0 .