Seeing Between the Atoms

New detector enables electron microscope imaging at record-breaking resolution.

Image courtesy of Cornell University

Resolution test of the new imaging methodology. Two single-layer sheets of molybdenum disulfide were placed on top of one another with a lattice misalignment of 6.8 degrees. The resulting moiré pattern provides pairs of atoms separated by a gradient of distances. Atoms that are separated by as small a distance as 0.4 ångströms are seen as distinct, indicative of 0.4  ångströms imaging resolution.

The Science

It set a Guinness world record. The highest resolution microscope in the world. It clearly shows features as small as 0.39 ångströms. For comparison, most atoms are about 2 to 4 ångströms in diameter. Previously, electron microscopes were limited by the electron lenses in the microscope. Now, a team based at Cornell University has combined a scanning transmission electron microscope (STEM) image reconstruction method with a new type of pixelated electron detector to obtain the highest resolution images ever seen.

The Impact

Electron microscopy is a fundamental tool used to understand many types of materials. The better the image resolution (the smallest features that can be imaged), the more information can be extracted. Until now, the resolution limit at energies that can safely image ultra-thin samples has been about an ångström. Since this is also about the size of a typical atom, atoms appear as fuzzy balls in the images. The new method is more than a factor of two better in resolution and offers sharp atomic details. The method provides a clear path to even higher resolution imaging.

Summary

For electron microscopes, the traditional approaches to improving resolution are increasing the energy of the electron beam, up to a point where the sample begins to be damaged, and adding correctors to improve the quality of the lenses. There is a limit to how much correction scientists can do if all these additional elements are to stay in alignment. Now, researchers report the highest magnification image ever obtained with a transmission electron microscope. They generated the image by passing electrons through a molybdenum disulfide sample to produce two-dimensional diffraction patterns and then using computer algorithms, packed with indirect scattering data, to produce the image. The image reveals the molybdenum and sulfur atoms with a resolution of 0.39 ång­ströms. Researchers believe the technique could lead to ultra-precise data about atoms in thin sheets. Further, it could lead to a way to obtain images of the bonds between every single atom without destroying the sample.

Contact

Sol M. Gruner
Cornell University
smg26@cornell.edu

David A. Muller
Cornell University
david.a.muller@cornell.edu

Funding

Detector development at Cornell University was supported by the Kavli Institute at Cornell for Nanoscale Science and the Department of Energy’s (DOE’s) Office of Science, Basic Energy Sciences. Electron microscopy and materials support came from the PARADIM Materials Innovation Platform in-house program by the National Science Foundation and the Air Force Office of Scientific Research. Researchers were funded the National Science Foundation and the Air Force Office of Scientific Research.

Publications

Y. Jiang, Z. Chen, Y. Han, P. Deb, H. Gao, S. Xie, P. Purohit, M.W. Tate, J. Park, S.M. Gruner, V. Elser, and D.A. Mueller, “Electron ptychography of 2D materials to deep sub-ångström resolution.” Nature 559, 343 (2018). [DOI: 10.1038/s41586-018-0298-5]

Related Links

Nature commentary on the research: A record-breaking microscope

Cornell Chronicle article: Electron microscope detector achieves record resolution

IFLScience! article: New electron microscope achieves record-breaking resolution

Microscopy and Analysis editorial: Record resolution from electron microscopy

University of Sheffield press release: Record-breaking microscope developed using methods pioneered by Sheffield scientists

Guinness World Records: Guinness Record: Highest resolution microscope

ScienceDaily news post: New high-capability solid-state electron microscope detector enables novel studies of materials

Highlight Categories

Program: BES , SUF

Performer: University

Additional: Collaborations , Non-DOE Interagency Collaboration