Abstract
In this chapter, we will focus on a specific X-ray-based technique among those employed in surface science and which is especially suitable for the study of self-assembled nanocrystals: Grazing Incidence Small Angle X-ray Scattering (GISAXS). We will first introduce the main field of investigation considered herein, with basic notions of X-ray scattering from surfaces, and then address basic concepts about GISAXS. Finally, we will describe a few relevant examples of studies, of nanostructured architectures, through ex situ and in situ experiments of grazing incidence X-ray scattering. This manuscript is focused on the former, showing that they can be performed by using laboratory instruments. In situ investigations still need synchrotron radiation sources in most cases; therefore, only a few examples selected from the literature are reported here, for the sake of completeness. The experiments described are mainly performed in the small angle range, providing information on the size and shape of nanocrystals, together with their spatial arrangement. Both 2D and 3D architectures are considered. In particular, GISAXS measurements of 2D superlattices of nano-octapods, performed both at a third generation synchrotron beamline and with a table-top set-up, are compared; the employed table-top set-up is described in a dedicated paragraph. Further examples of grazing incidence studies as performed by the authors with a table-top set-up are reported: a GISAXS study of 3D iron oxide nanocrystal superlattices, showing the importance of modelling in order to obtain structural information from data; a combined small/wide angle scattering (GISAXS/GIWAXS) study of 3D PbS nanocrystal superlattices; and a GIWAXS study of P3HT nanofibres, showing how the ordering at the molecular and atomic length scales can be obtained by exploring different angular ranges in the same grazing incidence geometry. Finally, selected examples of in situ GISAXS studies, performed with synchrotron radiation sources, are described.
Highlights
As of today, the synthesis of nanoparticles, nanocrystals and nanostructured architectures can be realized, on the www.intechopen.com
The accuracy in the determination of size and shape of the building blocks assembled in 1D, 2D or 3D architectures ‐ along with their mutual positions ‐ by Grazing Incidence Small Angle X‐ray Scattering (GISAXS), is strongly dependent upon the visibility of the interference fringes and, on the signal‐to‐noise and signal‐to‐background ratios in the X‐ray scattering pattern
Such a superlattice structure has been analysed through GISAXS for the first time and was chosen as the case study because of the complex shape of the building blocks, which leads to detail‐rich characteristic X‐ray scattering patterns
Summary
The synthesis of nanoparticles, nanocrystals and nanostructured architectures can be realized, on the www.intechopen.com. Of the specific synthesis approach, the physical and chemical properties of nanostructured materials are distinctly different from those of bulk matter with the same chemical composition. This difference is related to the reduced size, which leads to quantum confinement and/or to structural phase changes. Colloidal NCs are suitable vehicles to bring about the functions of crystals in a solution phase They are composed of an inorganic crystalline core and a surface shell of surfactant or ligand molecules that coordinate to unsaturated surface atoms. Last generation breeds of so‐called hybrid NCs (HNCs) are structurally elaborated multi‐material colloidal nanostructures, consisting of two or more different material domains interconnected through permanent chemical bonding, possibly forming heteroepitaxial interfaces. A few examples of in situ GISAXS studies selected from the literature ‐ performed with synchrotron radiation sources ‐ are described
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