Imagine a camera so powerful it can operate at attosecond speeds, or one trillionth of a second! The world’s newest and fastest microscope can capture the motion of an electron – a particle so fast it could orbit the Earth several times in just one second.

This is not just a fantasy; researchers at the University of Arizona have managed to make this new reality a reality. They have developed the world’s fastest electron microscope, a tool that is set to open new doors in the fields of physics, chemistry, bioengineering, materials science and beyond.

Mohammed Hassan, associate professor of physics and optical sciences, is leading 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 couldn’t see before – like electrons,” explains Hassan.

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

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 conventional light microscopes.

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

The principle of ultrafast electron microscopy, in which pulsed electron beams are generated using a laser, was first developed in the early 2000s.

This method significantly improved the temporal resolution of microscopes – that is, their ability to observe changes in a sample over a certain period of time.

Unlike conventional cameras, where image quality depends on 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

Despite these advances, there still remained 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 is a trillionth of a second.

These pulses could produce a series of images, similar to the frames in a movie, but scientists still miss the tiny changes in the behavior of the electrons that occur between those frames.

To overcome this limitation, Hassan and his team made a major breakthrough by generating a single attosecond electron pulse. This pulse is as fast as the electron’s proper motion, allowing the microscope to capture these elusive particles in a still image.

This performance improves the temporal resolution of the microscope and turns it into a high-speed camera that can capture movements that are not visible to the naked eye.

Building on Nobel Prize-winning research

This innovation did not come out of nowhere; it is based on the Nobel Prize-winning work of Pierre Agostini, Ferenc Krausz and Anne L’Huillière, who were awarded the Nobel Prize in 2023 for generating the first extreme ultraviolet radiation pulse measured in the attosecond range.

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

The first light pulse, the so-called “pump pulse,” injects energy into the sample, causing the electrons to move or change rapidly.

The second light pulse, the “optical gate pulse,” acts as a gate and creates a short window in which the single attosecond electron pulse is generated.

The speed of these gate pulses determines the resolution of the image. By precisely synchronizing these pulses, researchers can capture ultrafast processes at the atomic level.

“Improving the temporal resolution in electron microscopes has been long awaited and is the focus of many research groups – because we all want to see the electron movement,” says Hassan.

“These movements occur in attoseconds. But now, with our electron transmission microscope – we call it ‘attomicroscopy’ – we can achieve a temporal resolution in the attosecond range for the first time. For the first time, we can see parts of the electron in motion.”

Importance of attosecond electron microscopy

This breakthrough has profound implications. Understanding electron behavior is fundamental to many scientific fields.

In chemistry, for example, this could lead to new insights into the bonding and interaction of atoms, thus paving the way for novel chemical reactions and materials.

In bioengineering, this technology could provide a more detailed insight into biological processes and potentially lead to new treatments for diseases.

In addition, in the field of materials science, attomicroscopy could provide insight into how materials behave under stress or how they change at the atomic level, leading to the development of stronger and more resilient materials.

The ability to observe these processes in real time could lead to innovations in technology and medicine that were previously unattainable.

The development of the world’s fastest electron microscope represents a major advance 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 from the Departments of Physics and Optical Sciences that published the research article “Attosecond Electron Microscopy and Diffraction” in the journal Science Advances.

Hassan collaborated with Nikolay Golubev, assistant professor of physics, Dandan Hui, co-lead author and former research fellow in optics and physics who now works at the Xi’an Institute of Optics and Precision Mechanics of the Chinese Academy of Sciences, Husain Alqattan, co-lead author, a graduate of the University of Arkansas and assistant professor of physics at Kuwait University, and Mohamed Sennary, a doctoral student in optics and physics.

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