Scientists at Cornell University are working with a unique technique to record images to a higher level of detail than ever achieved before. The result is the highest resolution atomic image ever created.
The researchers magnified a 3D sample of a crystal 100 million times. The resultant image has twice the image resolution.
It earned them a Guinness World Record in 2018. They are now to break their record.
The researchers used electron ptychography to shoot a billion electrons per second at a target material. The beam of electrons aimed at a surface consists of a billion electrons each second.
With the beam’s slow movement, the released electrons hit the target from a variety of angles. The electrons can either pass straight through or bounce off of atoms along their path before they exit.
According to David Muller who is a physicist at Cornell, ptychography is like a game of dodgeball with your opponents in darkness. In this game of dodgeball, distinct atoms are the targets and electrons are dodgeballs.
The advanced detectors allow Muller to ‘see’ the atoms by seeing where the electrons stop. The electrons generate a speckle pattern that algorithms use to calculate the original location of the atoms and their shape.
Scientists have used ptychography to photograph materials with a thickness of one atom. Now, this study shows that it could capture ten to a hundred layers of atoms and more. The study was published in the journal Science.
Material scientists can rely on the technique to learn about the properties of materials with a 30-50 nanometer thickness. This thickness is so small that your nails grow more than that in a minute.
“They can look at stacks of atoms now, so it’s amazing,” declares University of Sheffield engineer Andrew Maiden. Maiden was not part of the new study, but he participated in developing ptychography as a technique. “The resolution is just staggering.”
This new development is a breakthrough in electron microscopy. Electron microscopes came about in the 1930s. They made it possible for scientists to look at objects of interest, like viruses.
The poliovirus, for example, is smaller than a light wavelength. Electron microscopes cannot deliver higher resolutions without a corresponding increase in the electron beam’s energy. This would give rise to an electron microscope that utilized enough energy to damage the material.
Researchers theorized about ptychography in the sixties’ as a possible solution to the problem. But scientists could not apply the technique for decades because they were working with limited computational power and limited capacity detectors.
Earlier versions of ptychography used x-rays and visible light instead of electron beams for imaging atoms. At the time, scientists were looking for ways to make electron microscopes better and this was so effective that it superseded electron ptychography. According to Muller, only true believers in ptychography still paid attention.
The long-term impact of this work will be better electronics. Computers and phones will be more efficient as well as powerful. Batteries will last longer because scientists would study the chemical reactions in greater detail.