Sub-ångström resolution ptychography in a scanning electron microscope at 20 keV
Bibliographic record
Abstract
Achieving sub-ångström (<1 Å) resolution in electron microscopy typically requires a high-energy (>30 keV) beam and a transmission electron microscope (TEM) fitted with an aberration corrector and a high efficiency, high pixel-count camera. The cost, space- and personnel-requirements of such TEMs is prohibitive for many laboratories. Low-energy (≤30 keV) scanning electron microscopes (SEMs), in comparison, offer a simpler, more compact, and cost-effective electron microscopy platform. Lower beam energies also have the potential to provide greater information from thin, light-element samples. Here, we demonstrate a sub-ångström resolution of 0.67 Å using a 20 keV SEM operated in transmission mode, enabled by ptychographic reconstruction. This resolution corresponds to a resolution-to-wavelength ratio of 7.8, surpassing previous results from electron ptychography and conventional imaging approaches. The gain in resolution is achieved through a multi-slice ptychographic algorithm incorporating diffraction distortion correction, coupled with a SEM fitted with a cold field emission source, immersion lens, simple projector lens, and a hybrid direct detector optimized for low-energy electrons. This approach holds immediate promise for high-resolution imaging of 2D materials and, with further development, may enable structural studies of small (<100 kDa) proteins.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".