Camera with a shutter speed of a trillionth of a second captures chaos in action: ScienceAlert

To take a picture, the best digital cameras on the market open their shutter for about four thousandths of a second.

To take a snapshot of atomic activity, you would need a shutter that clicks much faster.

With this in mind, scientists have introduced a method that can achieve a shutter speed of just one trillionth of a second, 250 million times faster than digital cameras. This makes it possible to capture something very important in materials science: dynamic disorder.

Put simply, these are clusters of atoms that move and dance around in a material in a certain way over a certain period of time – triggered, for example, by a vibration or a change in temperature. We do not yet fully understand this phenomenon, but it is crucial for the properties and reactions of materials.

The new superfast shutter system, which will be unveiled in 2023, will give us much more insight into what happens with dynamic disorder. The researchers call their invention the variable shutter atom pair distribution function, or vsPDF for short.

“It is only with this new vsPDF tool that we can really see this side of the materials,” said materials scientist Simon Billinge of Columbia University in New York.

“With this technique, we will be able to observe a material and see which atoms participate in the dance and which are left out.”

A faster shutter speed captures a more precise snapshot, which is helpful with fast-moving objects like jittering atoms. For example, if you use a low shutter speed on a photo of a sports game, the players in the frame will be blurry.

To achieve this amazingly fast capture, vsPDF uses neutrons to measure the position of atoms, rather than traditional photography techniques. The way neutrons hit and pass through a material can be tracked to measure the surrounding atoms, with changes in energy levels corresponding to adjusting the shutter speed.

These differences in shutter speed are as significant as the trillionth-of-a-second shutter speed: they are crucial to distinguishing dynamic disorder from the related but different static disorder—the normal background wobble at the site of atoms that does not enhance the function of a material.

“It offers us a completely new way to unravel the complexity of what happens in complex materials and uncover hidden effects that can enhance their properties,” said Billinge.

In this case, the researchers aimed their neutron camera at a material called germanium telluride (GeTe), which, due to its special properties, is often used to convert waste heat into electricity or electricity into cold.

The camera showed that GeTe still had a crystalline structure. on average, at all temperatures. However, at higher temperatures it showed more dynamic disorder, where the atoms converted motion into thermal energy, following a gradient corresponding to the direction of the spontaneous electrical polarization of the material.

By better understanding these physical structures, we can learn more about how thermoelectrics work, allowing us to develop better materials and devices – like the instruments that power Mars rovers when sunlight is absent.

Using models based on observations captured with the new camera, scientific understanding of these materials and processes can be improved, but much work remains to be done to make vsPDF a widely used testing method.

“We expect that the vsPDF technique described here will become a standard tool for tuning local and average structures in energy materials,” the researchers explained in their article.

The study was published in Natural materials.

An earlier version of this article was published in March 2023.