Researchers at the University of Arizona have developed the world’s fastest electron microscope, capable of capturing freeze-frame images of electrons in motion. This breakthrough could revolutionize our understanding of quantum physics and significantly impact various scientific fields.
Mohammed Hassan, associate professor of physics and optical sciences, let a group of researchers in developing the first transmission electron microscope powerful enough to capture images of electrons in motion. Image Credit: Amee Hennig
Imagine owning a camera so powerful it can capture freeze-frame photographs of a moving electron—an object traveling so fast it could circle the Earth multiple times in a single second. Researchers at the University of Arizona have developed the world’s fastest electron microscope that can achieve just that.
The researchers believe this breakthrough could pave the way for groundbreaking advancements in physics, chemistry, bioengineering, materials science, and beyond.
When you get the latest version of a smartphone, it comes with a better camera. 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.
Mohammed Hassan, Associate Professor, Department of Physics and Optical Sciences, University of Arizona
Transmission electron microscopes are advanced tools that magnify objects millions of times their actual size to reveal details that light microscopes cannot detect. Unlike light microscopes, these devices use electron beams instead of visible light. These electron beams pass through the sample, and their interactions are captured by lenses and detected by sensors to produce high-resolution images.
Developed in the 2000s, ultrafast electron microscopes use lasers to create pulsed electron beams, significantly enhancing the microscope's temporal resolution—its ability to capture rapid changes over time. Unlike traditional microscopes, which rely on the speed of a camera shutter, these ultrafast microscopes depend on the duration of electron pulses for their resolution.
The newly developed 'attomicroscope' features a dual-arm setup. The top arm converts a laser beam into ultraviolet pulses to generate ultrafast electron pulses within the microscope. The bottom arm splits another laser beam to control and regulate electron movement in the sample, allowing for detailed observation of fast atomic-level processes.
Previously, ultrafast electron microscopes operated with electron pulses lasting a few attoseconds—one quintillionth of a second—creating a series of images akin to movie frames. However, this approach missed the subtle changes occurring between frames. The University of Arizona team achieved a breakthrough by generating a single attosecond electron pulse, capturing electrons in motion with unprecedented clarity and enhancing the temporal resolution, much like a high-speed camera reveals otherwise invisible movements.
Their work builds on the Nobel Prize-winning research of Pierre Agostini, Ferenc Krausz, and Anne L’Huilliere, who were recognized in 2023 for generating the first extreme ultraviolet radiation pulse measurable in attoseconds.
Leveraging this achievement, the researchers developed a microscope that splits a powerful laser into two components: an ultrafast electron pulse and two ultrashort light pulses. The first pulse, or pump pulse, energizes the sample, prompting rapid electron movements. The second pulse, the optical gating pulse, creates a precise time window for the single attosecond electron pulse, which is crucial for capturing high-resolution images. Synchronizing these pulses enables the observation of ultrafast processes at the atomic scale.
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. 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.
Mohammed Hassan, Associate Professor, Department of Physics and Optical Sciences, University of Arizona
Journal Reference:
Hui, D., et al. (2024) Attosecond electron microscopy and diffraction. Science Advances. doi.org/10.1126/sciadv.adp5805