Influence of atomic coordination environment on the elastic-delocalization-induced artifacts in atomic-resolution elemental mapping

Abstract

Elastic electron delocalization displaces elemental signals from their true atomic positions, introducing artifacts in atomic-resolution elemental maps acquired via atomic-resolution energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS), which may potentially lead to misinterpretation of new structure. This study systematically investigates the influence of the atomic coordination environment on delocalization distance using a model structure of multi-element metal carbide Mo_1.33Er_0.67Nb₂AlC₃. Building on experimentally observed artifacts, model simulations reveal that EELS signals are more localized for light elements, while EDS signals are more localized for heavy elements. Furthermore, while the delocalization distance follows an increasing trend with larger convergence semi-angles and greater sample thicknesses, the atomic number of neighboring atoms has a negligible effect—typically resulting in deviations of less than 0.1 Å, which is negligible for current structural interpretation. In contrast, variations in interatomic spacing lead to non-monotonic changes in delocalization distance, with overall fluctuations remaining within 20 %, even as spacing nearly doubles. These insights offer a quantitative basis for identifying and interpreting imaging artifacts, contributing to more accurate atomic-scale structural analysis using EELS and EDS.