Ultrafast Electron Microscope Captures Heat Moving Through Material At The Speed Of Sound

A team of engineers and materials scientists from the University of Minnesota have developed an ultrafast electron microscope that has now been used to capture heat moving through materials at the nanoscale level. Interestingly, the heat is moving as fast as the speed of sound. The scientists observed that the heat moving through the material looked like ripples formed on a pond after a pebble is dropped in it. This recording of heat transfer could play a major role in designing our world's next-gen materials that could be widely used in applications such as personal electronics, transportation, power transmission as well as many alternative-energy technologies.

For reducing the human race's dependency on the fossil fuels, since decades, researchers are working on finding a technique that could help them in controlling the heat energy at atomic level so that they could recycle it.

Till date, scientists have found it to be a real challenge to capture images of the basic physical processes involved at the core of the thermal energy movement. The reason behind this is that the motion happens at speeds that range at many miles per second (too fast!) and at the scale of several nanometeres (too small!). Due to such extreme conditions, scientists had been on a look out of new imaging techniques.

The research team at University of Minnesota came up with the FEI Tecnaiâ„¢ Femto ultrafast electron microscope (UEM) that operates even at the molecular level and captures in femtoseconds (which is one 1000,000th of a 1000,000,000th of a second).

To achieve the desired results, the team excited the electrons using a brief laser pulse and heated tungsten diselenide and germanium (the crystalline semiconducting materials). The microscope was then used to capture extremely slow-motion videos of the waves of heat energy moving through those crystals.

Such mapping of oscillations of energy at the nanoscale could not only help understand the thermal energy motion, but also help researchers collect, control and precisely guide it to develop next-gen highly-efficient materials.

Check out the following video which shows heat moving through material at 6 nanometers per picosecond -

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