A camera with a shutter speed of one trillionth of a second captures the chaos in motion

To take pictures, the best digital cameras on the market open the shutter in four thousandths of a second. To capture atomic activity, you need a much faster shutter. Now scientists have found a way to achieve shutter speeds of one trillionth of a second, or 250 million times faster than those digital cameras. This allows him to capture something very important in materials science: dynamic disorder.

Simply put, clusters of atoms move and dance in a material over a period of time – for example, due to vibration or a change in temperature. This is not a phenomenon we fully understand yet, but it is crucial to the properties and reactions of materials. The new ultra-fast exposure system gives us a lot more insight into what’s going on with dynamic clutter. The researchers call their invention the variable gated atomic pair distribution function, or vsPDF for short.

“Only with this new vsPDF tool can we really see the material from another angle,” says materials scientist Simon Billinge of Columbia University in New York. “Through this technique, we will be able to observe the material and see which atoms are dancing and which are incubating it.”

Faster shutter speed provides a more accurate snapshot of time; this is useful for fast moving objects such as rapidly vibrating atoms. For example, use a slow shutter speed for a photo of a sports event and you’ll end up with blurry players in the frame.

To get incredibly fast imaging, vsPDF uses neutrons to measure the position of atoms instead of traditional photography methods. The path that neutrons take to enter and pass through material can be traced to measure surrounding atoms with changes in energy levels equivalent to adjusting the shutter speed.

These variations in shutter speed are significant, and shutter speeds in trillionths of a second are also important: they are vital for distinguishing dynamic disturbance from a related but distinct static disturbance (ordinary background vibration that does not improve the function of the material where the atoms are located). .

“This gives us a completely new way to reveal the complexity of what’s going on in complex materials, hidden effects that can enhance their properties,” Billinge says.

In this case, the researchers trained their neutron cameras on a material called germanium telluride (GeTe), which is commonly used to convert waste heat into electricity or electricity into cooling due to its special properties. The camera showed that GeTe remained crystalline on average at all temperatures. But at higher temperatures, the material exhibited greater dynamical disorder with atoms exchanging motion for thermal energy along a gradient corresponding to the direction of self-electrical polarization.

A better understanding of these physical structures will improve our knowledge of how thermoelectrics work, allowing us to design better materials and equipment, such as devices that power navigating vehicles in the absence of sunlight. Scientific understanding of these materials and processes can be improved with models based on observations made with the new camera. With all that said, there is still a lot of work to be done to prepare vsPDF for a widely used testing method.

“We expect the vsPDF technique described here to become a standard tool for reconciling local and intermediate structures in energetic materials,” the researchers wrote in their published paper.