Background optimization of powder electron diffraction for implementation of the e-PDF technique and study of the local structure of iron oxide nanocrystals

• Published in: Acta crystallographica. Section A, Foundations and advances Foundations and advances, 2023-09, Vol.79 (5), p.412-426
• Main Authors: Mogili, Naga Vishnu Vardhan, Verissimo, Nathália Carolina, Abeykoon, A M Milinda, Bozin, Emil S, Bettini, Jefferson, Leite, Edson Roberto, Souza Junior, João Batista
• Format: Article
• Language: English
• Subjects: background subtraction; Diffraction patterns; Distribution functions; Electron beams; Electron diffraction; electron pair distribution function (e-PDF); electron powder diffraction; electron reduced density function (e-RDF); Electrons; Inelastic scattering; Iron oxides; MATERIALS SCIENCE; Multiple scatter; nanocrystalline maghemite; Nanocrystals; Nanomaterials; Nanoparticles; Optimization; Scattering angle; Structural analysis; Subtraction
• ISSN: 2053-2733; 0108-7673; 2053-2733
• DOI: 10.1107/S2053273323005107

The local structural characterization of iron oxide nanoparticles is explored using a total scattering analysis method known as pair distribution function (PDF) (also known as reduced density function) analysis. The PDF profiles are derived from background-corrected powder electron diffraction patterns (the e-PDF technique). Due to the strong Coulombic interaction between the electron beam and the sample, electron diffraction generally leads to multiple scattering, causing redistribution of intensities towards higher scattering angles and an increased background in the diffraction profile. In addition to this, the electron-specimen interaction gives rise to an undesirable inelastic scattering signal that contributes primarily to the background. The present work demonstrates the efficacy of a pre-treatment of the underlying complex background function, which is a combination of both incoherent multiple and inelastic scatterings that cannot be identical for different electron beam energies. Therefore, two different background subtraction approaches are proposed for the electron diffraction patterns acquired at 80 kV and 300 kV beam energies. From the least-square refinement (small-box modelling), both approaches are found to be very promising, leading to a successful implementation of the e-PDF technique to study the local structure of the considered nanomaterial.