Watching electrons move in attoseconds with the world’s fastest microscope

Imagine a camera so powerful that it operates at attosecond speed, which is one quintillionth of a second! The world’s newest, fastest microscope can capture the motion of an electron — a particle so fast it could circle the Earth several times in just one second.

This is not just a fantasy; it’s the new reality achieved by researchers at the University of Arizona. They developed the world’s fastest electron microscope, a tool that promises to open new doors in the fields of physics, chemistry, bioengineering, materials sciences, and beyond.

Mohammed Hassan, an associate professor of physics and optical sciences, is at the helm of this project.

“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,” Hassan explains.

With this innovative tool, Hassan and his team hope to help the scientific community delve deeper into the quantum physics that govern electron behavior and movement.

Transmission electron microscopes

Transmission electron microscopes (TEMs) have long been a staple in scientific research. These devices can magnify objects up to millions of times their actual size, revealing details far beyond the capabilities of traditional light microscopes.

Instead of using visible light, TEMs direct beams of electrons through a sample. The interaction between these electrons and the sample generates detailed images, captured by a camera sensor.

The principle of ultrafast electron microscopy, which uses a laser to generate pulsed beams of electrons, was first developed in the early 2000s.

This method significantly enhanced the temporal resolution of microscopes — their ability to observe changes in a sample over time.

Unlike conventional cameras where image quality depends on the shutter speed, in a TEM, the resolution is determined by the duration of the electron pulses. The shorter the pulse, the clearer the image.

Attosecond electron pulses

Even with these advancements, there was still a gap in capturing the most fleeting moments of electron behavior. Previous ultrafast electron microscopes operated with electron pulses at speeds of a few attoseconds — an attosecond being one quintillionth of a second.

These pulses could produce a series of images, much like frames in a movie, but scientists were still missing the minute changes in electron behavior that occur between these frames.

To overcome this limitation, Hassan and his team achieved a significant breakthrough by generating a single attosecond electron pulse. This pulse is as fast as the electron’s own movement, allowing the microscope to capture these elusive particles in a freeze-frame.

This achievement enhances the microscope’s temporal resolution, making it akin to a high-speed camera that can capture movements invisible to the naked eye.

Building on Nobel-Winning Research

This innovation didn’t emerge from a vacuum; it builds on the Nobel Prize-winning work of Pierre Agostini, Ferenc Krausz, and Anne L’Huillière, who were recognized in 2023 for generating the first extreme ultraviolet radiation pulse measured in attoseconds.

Hassan’s team took this concept further by creating a microscope that splits a powerful laser into two components: a fast electron pulse and two ultra-short light pulses.

The first light pulse, known as the “pump pulse,” injects energy into the sample, causing electrons to move or undergo rapid changes.

The second light pulse, the “optical gating pulse,” acts as a gate, creating a brief window in which the single attosecond electron pulse is generated.

The speed of this gating pulse dictates the resolution of the image. By precisely synchronizing these pulses, researchers can capture ultrafast processes at the atomic 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,” says Hassan.

“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.”

Significance of attosecond electron microscopy

The implications of this breakthrough are profound. Understanding electron behavior is fundamental to many scientific fields.

In chemistry, for instance, it could lead to new insights into how atoms bond and interact, paving the way for novel chemical reactions and materials.

In bioengineering, this technology could offer a closer look at biological processes, potentially leading to new treatments for diseases.

Moreover, in the field of materials science, attomicroscopy might reveal how materials behave under stress or change at the atomic level, leading to the development of stronger, more resilient materials.

The ability to observe these processes in real-time could drive innovations in technology and medicine that were previously out of reach.

The development of the world’s fastest electron microscope is a leap forward in our ability to observe and understand the fundamental building blocks of the universe. Kudos to Mohammed Hassan and his brilliant team!

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Hassan led a team of researchers in the departments of physics and optical sciences that published the research article “Attosecond electron microscopy and diffraction” in the Science Advances journal.

Hassan worked alongside Nikolay Golubev, assistant professor of physics; Dandan Hui, co-lead author and former research associate in optics and physics who now works at the Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences; Husain Alqattan, co-lead author, U of A alumnus and assistant professor of physics at Kuwait University; and Mohamed Sennary, a graduate student studying optics and physics.

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