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This standard describes Small-angle X-ray scattering (SAXS) is a well-established method to obtain structural information on inhomogeneities in materials at the nanoscale, typically between 1 nm and 100 nm, and is thus perfectly suited for nanoparticulate systems. For spherical particles with a narrow size distribution, the observed oscillations of the scattered intensity as a function of the momentum transfer, which is directly related to the scattering angle and the wavelength of the incident X-rays, enable the size determination of nanoparticles. The case of particles with a homogeneous density profile has been described in ISO 17867:2020. The scattering intensity profile of particles with a non-uniform density profile deviates systematically from homologous particles with a constant density in their interior. To determine the density profile of a particle the electron density of the suspending medium needs to be known.
In this standard, only the structure of spherical core-shell particles of sufficiently narrow size distribution is treated. The shape of the scattering curves can be compared quantitatively using analytically calculated structural models of core-shell particles. In particular, the particle form factors can be calculated based on the radius of the core of the particle rc, the thickness of the shell of the particles ts, and the electron densities of the core ρc and shell ρs. Furthermore, this International Standard is limited to dilute systems. A dilute system in the sense of SAXS means that particle interactions are absent. In the case of long-range interactions (Coulomb forces between the particles), special care must be taken, and a reduction of the concentration might be necessary.
Reģistrācijas numurs (WIID)
88154
Darbības sfēra
This standard describes Small-angle X-ray scattering (SAXS) is a well-established method to obtain structural information on inhomogeneities in materials at the nanoscale, typically between 1 nm and 100 nm, and is thus perfectly suited for nanoparticulate systems. For spherical particles with a narrow size distribution, the observed oscillations of the scattered intensity as a function of the momentum transfer, which is directly related to the scattering angle and the wavelength of the incident X-rays, enable the size determination of nanoparticles. The case of particles with a homogeneous density profile has been described in ISO 17867:2020. The scattering intensity profile of particles with a non-uniform density profile deviates systematically from homologous particles with a constant density in their interior. To determine the density profile of a particle the electron density of the suspending medium needs to be known.
In this standard, only the structure of spherical core-shell particles of sufficiently narrow size distribution is treated. The shape of the scattering curves can be compared quantitatively using analytically calculated structural models of core-shell particles. In particular, the particle form factors can be calculated based on the radius of the core of the particle rc, the thickness of the shell of the particles ts, and the electron densities of the core ρc and shell ρs. Furthermore, this International Standard is limited to dilute systems. A dilute system in the sense of SAXS means that particle interactions are absent. In the case of long-range interactions (Coulomb forces between the particles), special care must be taken, and a reduction of the concentration might be necessary.
