Small-angle X-ray scattering simulations on a single Pt nanoparticle system: An analysis of structural characteristics

Abstract

Small-angle X-ray scattering (SAXS) is an operando structure characterization tool that is unique in its ability to detect diverse nano-particulate materials. Guinier approximation and form factor can efficiently extract statistically meaningful structure information such as size and morphology from SAXS data. Herein, by employing a simulation of scattering intensities via a lattice-atoms-based code, we demonstrate quantitative correlation between SAXS data and the structural characteristics in real space for single Pt nanoparticle with different size and structure motifs. It is shown that, for particles with varied morphologies, the symmetry of 2D patterns strongly depend on the orientation of facets. However, the oscillation in frequencies and amplitudes of 1D profile, the azimuthally averaged and integrated 2D patterns, are not so sensitive to structure motifs. Regardless of particle shapes, the discrepancy between the actual particle sizes and evaluated values from 1D profile, obtained by utilizing the form factors or Guinier approximation, are pretty small. Such discrepancy is more apparent for smaller particles, attributed to strong size-dependence of surface constitution, especially for spheres. By conducting a detailed analysis of the correlation between real-space and reciprocal-space lattice information, this work highlights the continuous-to-discrete transition of nano-objects and paves the way to accurately determining structural features from SAXS data.