Incredible Microscope Sees Atoms at Record Resolution
martyb writes:
Incredible Microscope Sees Atoms at Record Resolution:
In 2018, Cornell researchers built a high-powered detector that, in combination with an algorithm-driven process called ptychography, set a world record by tripling the resolution of a state-of-the-art electron microscope.
As successful as it was, that approach had a weakness. It only worked with ultrathin samples that were a few atoms thick. Anything thicker would cause the electrons to scatter in ways that could not be disentangled.
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.
[...] Ptychography works by scanning overlapping scattering patterns from a material sample and looking for changes in the overlapping region.
"We're chasing speckle patterns that look a lot like those laser-pointer patterns that cats are equally fascinated by," Muller said. "By seeing how the pattern changes, we are able to compute the shape of the object that caused the pattern."
The detector is slightly defocused, blurring the beam, in order to capture the widest range of data possible. This data is then reconstructed via complex algorithms, resulting in an ultraprecise image with picometer (one-trillionth of a meter) precision.
"With these new algorithms, we're now able to correct for all the blurring of our microscope to the point that the largest blurring factor we have left is the fact that the atoms themselves are wobbling, because that's what happens to atoms at finite temperature," Muller said. "When we talk about temperature, what we're actually measuring is the average speed of how much the atoms are jiggling."
Journal Reference:
Zhen Chen, Yi Jiang, Yu-Tsun Shao, et al. Electron ptychography achieves atomic-resolution limits set by lattice vibrations [$], Science (DOI: 10.1126/science.abg2533)
Read more of this story at SoylentNews.