Small-Angle X-ray Scattering by Nanostructured Materials

Abstract

Grazing incidence small-angle X-ray scattering (GISAXS)This chapter contains the basic theory of small-angle X-ray scattering (SAXS) and its applications to low-resolution studies of nanostructured materials. The primary purpose is to explain how to obtain structural information from simple systems whose low-resolution structure can be described by a two-electron density model, consisting of either homogeneous nanoparticles embedded in a (solid or liquid) medium with constant electron density or two-phase bicontinuous systems. The presented SAXS theory and the examples of applications refer to different procedures for determinations of geometrical parameters associated to nanoparticles or clusters in dilute solution, spatially correlated nanoparticles, and more general two-phase systems, namely, particle radius of gyration, interface area, size distribution, fractal dimension, and interparticle average distance. Other described applications are in situ SAXS studies of mechanisms involved in transformation processes leading to nanostructured materials such as those occurring in nanophase separation and along the successive steps of sol–gel routes. One section is dedicated to present the basic concepts and describes an application of grazing incidence small-angle scattering (GISAXS), which allows for studying nanostructured thin films and thin layers located close to the external surface of solid substrates. Most of the reported applications refer to nanostructured materials obtained by sol–gel processing and are based on experimental results published by the author and collaborators.Grazing incidence small-angle X-ray scattering (GISAXS)