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Imaging atoms – seeing the impossibly small

John Healy

When not merely obscured in our field of view, things which we cannot see – that are essentially invisible – often may be either impossibly distant or impossibly small (among other factors). That’s why we have telescopes and microscopes.

At cosmic scales, imaging a black hole was like seeing something spanning “the size of a period at the end of a sentence if you were looking at it from Earth and that period was in a leaflet left on the moon.”

At microscopic scales, can we see atoms? What’s changed in the last ~50 years?

So, how small can we go in imaging atoms? Beyond the direct imaging of conventional electron microscopes, there’s reconstructive imaging based on pattern processing – for highly ordered atomic lattices. An enhancement which extracts higher resolution geometries from scattered electrons [1].

• Phys.org > “Researchers see atoms at record resolution” by David Nutt, Cornell University (May 21,2021)

(quote) In 2018, Cornell researchers built a high-powered detector that, in combination with an algorithm-driven process called ptychography [the method is time-consuming and computationally demanding], set a world record by tripling the resolution of a state-of-the-art electron microscope [for ultra-thin samples that were a few atoms thick].

Now a team, again led by David Muller, the Samuel B. Eckert Professor of Engineering, has bested its own record by a factor of two with an electron microscope pixel array detector (EMPAD) that incorporates even more sophisticated 3D reconstruction algorithms.

The resolution is so fine-tuned, the only blurring that remains is the thermal jiggling of the atoms themselves.

Notes

[1] Historically, much like using X-ray crystallography to construct atomic and molecular structure.

Terms
  • Electron ptychographic reconstruction
  • Speckle patterns (coherent interference patterns)
  • Picometer
  • Phase velocity
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• Ultimate why? > Comment 2-14-2018 re a prize winning photo of a single atom.

3 thoughts on “Imaging atoms – seeing the impossibly small”

  1. Speaking of making the invisible visible, in particular, seeing in wavelengths beyond visible light: imagine having an alternate pair of “sunglasses” that permits seeing scenes in infrared. Similar to your other frames, just as comfortable and lightweight.

    • Phys.org > “New thin-film tech to revolutionize night vision” by Australian National University (June 15, 2021)

    The first-of-its-kind thin film [proof-of-concept, based on nanoscale crystals], described in a new article published in Advanced Photonics, is ultra-compact and one day could work on standard glasses.

  2. Imaging a protein with atomic level detail.

    • Caltech Weekly > Caltech > “Some Assembly Required: How a Cellular Machine Builds Itself” (July 8, 2021)

    (quote) … the endoplasmic reticulum membrane protein complex (EMC), which is present in all eukaryotes, … acts as a gateway between the interior of the cell and the cell’s outer membrane, and behaves as a kind of border control through which only certain proteins can pass.

    In research published last year, the Voorhees lab created the first-ever images of the EMC with atomic-level detail, revealing the blueprint of the structure.

  3. Something lacking at institutional scale ~50 years ago was interdisciplinary research / collaboration. I’m glad to see another example in the news.

    • Caltech Magazine > “Biology through the Eyes of a Physicist” by Whitney Clavin (Features, Summer 2021) – A Look At The Multifaceted, Interdisciplinary World Of Biophysics

    (quote) The discovery of the double helix exemplifies the multifaceted field of biophysics, in which biology is viewed and better understood through the lens of physics. In this case, the X-ray-based tools of physicists were applied to living matter …

    Cissé [recently hired physics professor Ibrahim Cissé] specializes in visualizing single molecules inside living cells using a technique called super-resolution imaging, in which the limits of optical light itself, specifically the diffraction limit, are surpassed and cellular structures on the scale of a few nanometers can be resolved.

    Cissé and his team have adapted and further developed the tool of super-resolution microscopy to study clusters of molecules that are not static but rapidly assemble and disassemble in living mammalian cells.

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