Since the 1930s when the first transmission electron microscope (TEM) was created by Ernst Ruska, we have been able to peer into the micro- and nanoscale world thanks to electrons. Now, 85 years later, new advances by the David Muller group at Cornell University have improved our resolution down to 0.39 angstroms (1/10,000,000,000 of a meter), giving us an unprecedented look at the very fundamental building blocks of matter.
0.39-angstrom image of molybdenum disulfide (bottom right) shows a sulfur vacancy that is unclear in lower-resolution images. via DOI 10.1038/s41586-018-0298-5
What is a Transmission Electron Microscope (TEM)?
In a vacuum, electrons can act just like light, existing as both waves and particles. Transmission electron microscopes pass electrons through ultrathin samples, just like light passes through the film of a movie projector, magnifying the information for us to see. Since electrons have a much smaller wavelength than light, the objects they can show and magnify are proportionally smaller as well.
How small are we talking?
When the initial TEM was created it was able to resolve, or make visually distinct, features as close together as 1,000 angstroms, the same as the best light microscope. While this allowed us to view an incredible microscopic world, atomic bonds are single angstroms long. With a resolution of 0.39 angstroms, Muller’s new instrumentation can clearly see not just atoms but the spaces between them as well.
Why is this so critical?
Current, cutting-edge electronics exist on the nanoscale. Studying novel materials for electronics applications, therefore, requires atomic-level information. Conventional electron microscopes can attain this resolving power, but need very high energy electron beams to do so, which can destroy the sample being studied. The Muller Group, using Thermo Scientific STEM (scanning TEM) instrumentation in conjunction with their novel detector, was able to create a new EM technique that has incredible resolving power while remaining gentle on the sample. This is great news for the study of delicate materials like molybdenum disulfide, which they were able to clearly image in their latest ground-breaking study. Looking forward, this opens the door to the detailed analysis of countless sensitive synthetic and natural materials.
To learn about more ways in which sub-angstrom resolution is changing not just the face of microscopy but science itself, read the Nature article. Stay up-to-date with cryo-EM news by following us on Twitter (@thermosciEMSpec).
Dr. Christian Maunders is the TEM Product Marketing Manager at Thermo Fisher Scientific.
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