Scientists see atoms with standard accuracy

In 2018, Cornell scientists built a high-performance detector in combination with an algorithm-based process called ptychography. World record Triple resolution for an advanced electron microscope.

No matter how successful it was, this approach was weak. I only worked with the ultra-thin specimens, which were few Atoms thick. Anything stronger would cause the electrons to be scattered inseparably.

Now a team led by David Mueller, professor of engineering at Samuel B. Eckert, has gone beyond its multiplication factor record with the Pixel Matrix Electron Microscopy Detector (EMPAD), which includes more advanced 3D reconstruction algorithms.

The accuracy is finely tuned and the only distortion remaining is the thermal vibration of the atoms themselves.

The documentary for Electron Ptychography Achiives Atomic-Resolution Limits was published on May 20 in Science. The lead author of the article is postdoctoral researcher Zhen Chen.

“It’s not just a new record,” Mueller said. “He achieved a system that would, in fact, be the ultimate in precision. Now we can easily figure out where the atoms are. This opens up a lot of new possibilities for scaling things up, which is what we wanted to do, and it also solves a long-term problem – it eliminates the multiple scattering of the beam.” In the sample that Hans Bethe developed in 1928 – which prevented us from doing that. So in the past. “

Ptychography works by scanning overlapping scatter patterns from a sample of material and looking for changes in the overlapping region.

“We are catching on with spotted patterns that are very similar to the laser pointer patterns that fascinate cats,” Mueller said. “When we see how the pattern changes, we can calculate the shape of the object that caused the pattern.”

The detector is slightly indeterminate, Blur beamIn order to obtain the widest possible range of data. This data is then reconstructed using complex algorithms, resulting in a super-resolution image with a micrometer (one trillionth of a meter) resolution.

“With these new algorithms, we can now correct all of our microscopic fuzziness to the point where our biggest blur is the fact that the atoms themselves oscillate because they happen to the atoms at the final temperature,” Mueller said. The average speed at which the atoms vibrate. “

Scientists were able to break the record again by using a substance consisting of heavier atoms with less fluctuation or cooling of the sample. But even at zero temperature, the atoms still experience quantum fluctuations, so the improvement wouldn’t be very large.

This newer form of standard electron imaging would allow scientists to locate individual atoms in all three dimensions if they could be masked using other imaging methods. Scientists will also be able to find impurity atoms in unusual configurations and photograph them with their vibrations, one after the other. This can be particularly useful for imaging semiconductors, catalysts, and quantum materials – including those used in quantum computation – as well as for analyzing atoms at boundaries where materials are bound together.

The imaging method can also be applied to cells, stronger biological tissues, or even synaptic connections in the brain – which Mueller refers to as “communication on demand”.

Although this method is computationally time consuming and consuming, it can be made more efficient with the help of more powerful computers along with machine learning and faster detection devices.

“We want to apply this to everything we do,” said Mueller, who directs the Kavli Institute at Cornell Nanoscience and co-chairs the Nanoscale Engineering Task Force (NEXT Nano), which is part of Cornell’s Radical Collaboration. . “Until now, we’ve all been wearing really bad glasses. And now we have a really good couple. Why don’t you take your old glasses off and put on new ones and use them all the time?”