A team of physicists at the University of Arizona has developed the world’s fastest electron microscope, capable of capturing electrons traveling at 7,920,000 km/h.
The new device is an upgraded version of a transmission electron microscope, which takes images of moving electrons by firing electron pulses at a time span of a billionth of a billionth of a second. This is a major achievement because electrons move so fast, about 2,200 kilometers per second, or 7,920,000 kilometers per hour, that they can circle the Earth in just 18.4 seconds. The new research was published in the journal Science Advances August 21
The team hopes that using this microscope on tiny electrons will yield new insights into how they move. “This transmission electron microscope is like a very powerful camera in the latest version of a smartphone. It allows us to image things that we couldn’t see before, like electrons,” said lead author Mohammed Hassan, associate professor of physics and optics at the University of Arizona.
How electrons arrange and rearrange themselves inside atoms and molecules is a major problem in both physics and chemistry, but the fact that they move so quickly has been a major challenge for experts. In the early 2000s, to create exposure times that could capture the motion of electrons, physicists developed a method for generating attosecond (or billionths of a billionth of a second) pulses. It was this research that gave the trio Pierre Agostini, Ferenc Krausz and Anne L’Huilliere Nobel Prize in Physics 2023.
By reducing microscope exposure times to the scale of a few attoseconds, physicists have deciphered how electrons carry electrical charges, how they behave inside semiconductors and liquid water, and how chemical bonds between atoms are broken. But the scale of a few attoseconds is still too large to capture individual electron motions.
In the new study, the team improved the electron gun until it produced pulses lasting just one attosecond. These pulses hit the sample, and as the electrons pass through, they slow down and change the shape of the electron beam wavefront. The slowed-down electron beam is then amplified by a lens, and then hits a fluorescent material that glows 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 moving,” Hassan said. Hassan and colleagues believes that the new research will lead to breakthrough advances in physics, chemistry, bioengineering, materials science and many other fields.