To take a picture, the best digital cameras on the market open their shutter for about four thousandths of a second.
To capture atomic activity, you need a shutter that clicks faster.
With this in mind, scientists uncovered 2023 This is a method that achieves shutter speeds of just one trillionth of a second, or 250 million times faster than a digital camera. This allows it to capture something very important in materials science: dynamic disorder.
Watch the video below for a summary of their findings:
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Simply put, this is when groups of atoms move and dance in a material in specific ways over a certain period of time, such as triggered by vibrations or changes in temperature. This is not a phenomenon we fully understand, but it is crucial to the properties and reactions of materials.
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The ultra-fast shutter speed system allows us to gain greater insight into dynamic turmoil. The researchers call their invention “Variable Shutter Atom Pair Distribution Function,” or vsPDF for short.
“Only with this new vsPDF tool can we really see this side of the material,” says materials scientist Simon Billinge of Columbia University in New York.
“With this technology, we will be able to look at a material and see which atoms are dancing and which atoms are dancing.”
Faster shutter speeds capture more precise snapshots of time, which is helpful for fast-moving objects such as rapidly shaking atoms. For example, if you use a slow shutter speed in a photo of a sports match, the players in the final frame will be blurry.
Illustrations showing the atomic structure of GeTE at slower (left) and faster (right) shutter speeds. (Jill Hemman/ORNL, U.S. Department of Energy)
To achieve incredibly fast captures, vsPDF uses neutrons to measure the positions of atoms instead of traditional photography. The way neutrons hit and travel through materials can be tracked to measure surrounding atoms, with changes in energy levels equivalent to adjustments in shutter speed.
These changes in shutter speed, as well as shutter speeds of trillionths of a second, are important: they are crucial for sorting out dynamic disorder from related but distinct static disorder—normal background jitter at atomic points does not enhance the functionality of the material.
“It gives us a completely new way to address the complexities that occur in complex materials and the hidden effects that can enhance their properties,” Billinger said.
In this case, the researchers pointed the neutron camera at a material called germanium telluride (GeTe), which is widely used to convert waste heat into electricity or electricity into cooling due to its special properties.
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The camera shows that GeTe still maintains its crystal structure, On average, at all temperatures. But at higher temperatures, it exhibits more dynamic disorder, with atoms exchanging motion for thermal energy following a gradient that matches the direction of the material’s spontaneous electrical polarization.
A better understanding of these physical structures could improve our understanding of how thermoelectricity works, allowing us to develop better materials and devices, such as instruments that would power a Mars rover in the absence of sunlight.
Scientific understanding of these materials and processes can be improved through models based on observations captured by new cameras. However, there is still a lot of work to be done before vsPDF becomes a widely used testing method.
“We anticipate that the vsPDF technique described here will become a standard tool for harmonizing local and average structures in energy materials,” the researchers explain in their paper.
The study was published in natural materials.
An earlier version of this article was published in March 2023.
