Disentangle the microscopic defect processes governing NaCl damage evolution

Determine which individual defect processes—migration, aggregation, and recombination—govern the frame-to-frame evolution and crystallographically constrained void formation in electron-irradiated, unencapsulated NaCl under the reported 4D-STEM conditions.

Background

The paper observes that beam-induced damage in unencapsulated NaCl develops into square-faceted or stepped regions aligned with the crystal’s ⟨100⟩ directions, rather than following the raster-scan geometry. Frame-to-frame changes further show that the damage is not strictly cumulative: defects can partially recede in one location while extending along a neighboring crystallographic direction.

These observations are consistent with a dynamic defect population involving migration, aggregation, and recombination. However, the measurements do not resolve which of these individual microscopic processes contributes to the observed evolution. Establishing their respective roles would provide a more general understanding of the damage kinetics beyond the specific experimental conditions studied.

References

The present measurements cannot unambiguously distinguish these individual processes, but they demonstrate that the observed void formation is the result of an evolving defect population rather than a direct imprint of the electron beam, and scan pattern, geometry.

— Pushing the Dose Limit of Atomic-Resolution Imaging: A 4D-STEM case study of NaCl  (2609.17208 - Chennit et al., 15 Sep 2026) in Section 5.1, “Crystallographically constrained evolution of beam-induced damage”