A team of physicists at the University of Arizona has developed the world’s fastest electron microscope, capable of capturing electrons moving at speeds of 7,920,000 km/h.
The new device is an upgraded version of the transmission electron microscope, which photographs moving electrons by firing electron pulses with a time resolution of one attosecond. This is a significant achievement because electrons move extremely fast, at approximately 2,200 km/s or 7,920,000 km/h, which means they could circle the Earth in just 18.4 seconds. The new research was published in the journal Science Advances on August 21.
Simulation of atto microscope technology (left), microscope and surrounding equipment (right). (Photo: Mohammed Hassan/University of Arizona).
The research team hopes that using this microscope on tiny electrons will lead to new discoveries about how they move. “This transmission electron microscope is like a very powerful camera in the latest smartphone version. It allows us to take pictures of things we couldn’t see before, like electrons,” said the lead author of the study, Mohammed Hassan, an associate professor of physics and optics at the University of Arizona.
How electrons self-organize and rearrange within atoms and molecules is a crucial question in both physics and chemistry, but their rapid movement poses a significant challenge for experts. In the early 2000s, to create exposure times capable of capturing electron motion, physicists developed a method to generate attosecond pulses (or one quintillionth of a second). This research also earned the trio of Pierre Agostini, Ferenc Krausz, and Anne L’Huilliere the 2023 Nobel Prize in Physics.
By reducing the exposure time of the microscope to the scale of a few attoseconds, physicists have decoded how electrons carry charge, how they operate within semiconductors and liquid water, and how chemical bonds between atoms are broken. However, a few attoseconds is still too large a scale to capture the individual motion of electrons.
In the new study, the team of experts improved the electron gun until it produced pulses lasting just one attosecond. These pulses are fired into a specimen, and as electrons pass through, they slow down and alter the shape of the electron beam’s wavefront. Next, the slowed electron beam is amplified by a lens and then strikes a fluorescent material. This material emits light when the electron beam hits it.
“We can achieve attosecond time resolution with our transmission electron microscope, and we call it ‘atto microscopy.’ For the first time, we can see parts of electrons in motion,” Hassan stated. Hassan and his colleagues believe that this new research will lead to groundbreaking advancements in physics, chemistry, biomedical engineering, materials science, and many other fields.
