Dose-Fractionated Electron Ptychography for Atomic-Resolution Imaging Under Ultra-Low Dose

Acquiring atomic-level structural information from electron beam-sensitive materials such as two-dimensional crystals, zeolites, metal-organic frameworks, hybrid perovskites, and battery materials, remains a major challenge due to strict dose limits and high sensitivity to experimental errors. Electron ptychography is well suited for low-dose imaging thanks to its high dose efficiency and robustness to aberrations, yet achieving atomic resolution (<2 Å) below 100 e⁄Ų remains elusive. Here, we present a dose-fractionated ptychographic data acquisition and processing strategy that decouples the dose-per-frame from the total dose, enabling higher-resolution reconstructions under severe dose constraints. Our method achieves 1.58–2.72 Å resolution of single-layer MoS₂ at electron doses well below 100 e⁄Ų, and allows direct detection of sulfur vacancies using only one-fifth (1038 e⁄Ų) of the dose that conventional ptychographic framework typically required. This framework offers a robust, generalizable pathway for non-destructive structural analysis of a wide range of dose-sensitive materials including biological specimens under atomic resolution.