SIG4 (ECA) Distinguished Publication Award 2025

The “Distinguished Publication Award 2025”, presented by the Special Interest Group on Electron Crystallography (SIG4) of the European Crystallographic Association (ECA), recognizes the most outstanding paper published in 2024, celebrating significant advancements and applications in the field of electron crystallography. Nine nominated publications were evaluated based on five specific criteria covering innovation, complexity, high-quality research, impact and broad scope of the work. The jury was formed by four internationally recognized experts in electron diffraction methods that were not co-authors of any of the submitted publications to avoid any biasing during the evaluation. SIG4 extends its thanks to their willingness, engagement and professionalism.

This year’s winner is the paper titled Ionisation of atoms determined by kappa refinement against 3D electron diffraction data by Ashwin Suresh, Emre Yörük, Małgorzata K. Cabaj, Petr Brázda, Karel Výborný, Ondřej Sedláček, Christian Müller, Hrushikesh Chintakindi, Václav Eigner & Lukáš Palatinus, published on October 21, 2024, in Nature Communications, 15, 9066.

This work demonstrates that 3D electron diffraction (3D ED), traditionally used for locating atom positions and ignoring bonding effects and charge redistribution, can now be used to extract quantitative charge density information using the kappa refinement model. Unlike previous approaches limited to the independent atom model or relying on external charge-density inputs (TAAM or HAR techniques), this method extends the refinement model to include valence electron populations and their spatial contraction/expansion. The study shows that 3D ED is not only effective for light-atom systems, such as boranes, but also excels at probing heavy atoms like Cs, Pb, and Lu, where X-ray diffraction often struggles. By combining dynamical diffraction theory, crystal shape modelling, the kappa refinement procedure, and further validation against DFT-based electron densities, the authors establish 3D ED as a powerful tool for experimental charge density analysis on nanocrystals, thus marking a significant advance beyond its traditional role in structural determination.

The jury agreed about the difficulty to select just one publication for the award as all nominated publications showed very high-quality research standards. Nonetheless, the work of Suresh et al. stood out from the others, highlighting the pursuit of better modelling and physical interpretation of the retrieved electrostatic potential and ultimately better crystal structure models from electron diffraction data.

We congratulate the winners, and we look forward to further advances in the field of electron crystallography.