Exploiting GISAXS for the Study of a 3D Ordered Super lattice of Self-Assembled Colloidal Iron Oxide Nanocrystals
Abstract
A three-dimensional (3D) ordered superlattice of colloidal iron oxide nanocrystals obtained by magnetic-field-assisted self-assembly has been studied by grazing incidence small angle X-ray scattering (GISAXS). A new model to simulate and interpret GISAXS patterns is presented, which returns the structural and morphological details of 3D nanocrystal-built supercrystals.
The model is applied to a sample with a suitable surface morphology, allowing the observation of "volume diffraction" even at extremely low grazing incidence angle. In this particular case, the average fcc-like stacking of the nanocrystals (building blocks), their spherical shape, and statistical information on their size distribution and positions within the superlattice have been safely deduced The proposed model is expected to be amendable for the analysis of more complex structures and applicable to a large variety of nanocrystal-based assemblies.