Combining reverse Monte Carlo analysis of X-ray scattering and extended X-ray absorption fine structure spectra of very small nanoparticles

Abstract

Finite size effects in partial pair distribution functions generate artefacts in the scattering structure factor and scattering intensity. It is shown how they can be overcome using a binned version of the Debye scattering equation. Accordingly, reverse Monte Carlo simulations are used for very small nanoparticles of LaFeO3 with diameters below 10 nm to simultaneously analyse X-ray scattering data and extended X-ray absorption fine structure spectra at the La K and Fe K edges. The structural information obtained is consistent regarding local structure and long-range order.

Very Small Nanocrystalline Tin Dioxide Particles: Local-, Crystal-, and Micro-Structure

“…A cluster model based on MD simulations is slightly worse than the nanocrystal model. The sample with the smallest crystallite size is also investigated by simultaneously refining WAXS and EXAFS data (Figure ) using the nanocrystal model (a cluster model generated from Rietveld results; Figure ). The EXAFS data for sample 2p above 12 Å –1 contains not only noise (Figure ) but also structural information as can be seen by comparing residual and refined spectrum (Figure top right).…”

“…RMC analysis of the EXAFS data is performed using the rmcxas code − starting from different initial atomic configurations as models. RMC analysis models the EXAFS data by refining a physical model (atom configuration) based on the difference between experimental and simulated EXAFS spectra via the partial pair distribution functions (pPDFs) using a Metropolis Monte Carlo algorithm .…”