Physicists at the University of Arizona have achieved a significant breakthrough in imaging the subatomic world. They have developed the world’s fastest electron microscope, capable of capturing events that last just one attosecond — a quintillionth of a second.
These cutting-edge instruments are vital for studying ultrafast processes. An “attomicroscope” operates on a scale that dwarfs even the fastest cameras. Essentially, it freezes time to observe events at the particle level, including moving electrons. An attosecond is a staggeringly brief moment — there are as many attoseconds in a single second as there are seconds in 31.7 billion years.
Picking Up the Pace
Electron microscopes magnify objects by directing beams of electrons through a sample. But, traditionally, they are limited in how they capture movement. Camera lenses capture interaction between the electrons and the sample, and a camera sensor detects it in order to generate detailed images of the sample.
While past innovations allowed scientists to observe electron behavior over time, they were still missing crucial details. It was the microscopic equivalent of seeing a movie in slow motion but with annoying missing frames in between.
Until now, the shortest event ever recorded was 43 attoseconds long, an achievement previously described as “the shortest controlled event ever created by humankind.” However, the University of Arizona team has now outdone this by achieving an unprecedented one-attosecond resolution. The faster the pulse, the better the image quality.
“When you get the latest version of a smartphone, it comes with a better camera,” said Associate Professor Mohammed Hassan. “This transmission electron microscope is like a very powerful camera in the latest version of smartphones; it allows us to take pictures of things we were not able to see before — like electrons. With this microscope, we hope the scientific community can understand the quantum physics behind how an electron behaves and how an electron moves.”
The research builds on the 2023 Nobel Prize-winning work of Pierre Agostini, Ferenc Krausz, and Anne L’Huillier, who pioneered the creation of ultrashort light pulses in the attosecond range. By refining these techniques and applying them to electron microscopy, the University of Arizona team has opened a new frontier in scientific imaging.
A Leap Forward in Microscopy
Their attosecond system involves a powerful laser split into two components: a fast electron pulse and two ultrashort light pulses. The first light pulse, called the pump pulse, energizes a sample, triggering electron movement or other rapid changes. The second pulse, known as the optical gating pulse, creates a brief window to generate a single attosecond electron pulse. The timing of this gating pulse determines the image resolution. By precisely synchronizing these pulses, researchers can control when the electron pulses probe the sample, allowing them to observe ultrafast atomic-level processes.
This advancement is poised to impact a wide array of fields, from physics and chemistry to materials science and bioengineering. By providing an unprecedented view into the behavior of electrons, the microscope could unlock new insights into quantum mechanics, the development of new materials, and even biological processes at the molecular level.
“The improvement of the temporal resolution inside of electron microscopes has been long anticipated and the focus of many research groups, because we all want to see the electron motion,” Hassan said. “These movements happen in attoseconds. But now, for the first time, we are able to attain attosecond temporal resolution with our electron transmission microscope — and we coined it ‘attomicroscopy.’ For the first time, we can see pieces of the electron in motion.”
The findings appeared in the journal Science Advances.
