Researchers at the University of Arizona have developed the world’s fastest electron microscope that can see electrons moving.
This transmission electron microscope is like a super-advanced camera that can capture things previously unseen—like electrons. Through this microscope, researchers expect to understand how electrons behave and move in quantum physics.
Scientists used a transmission electron microscope to magnify objects up to millions of times their actual size. Instead of using visible light, a transmission electron microscope uses beams of electrons to pass through the sample. The interaction between the electrons and the sample is captured by lenses and detected by a camera sensor to create detailed images.
Ultrafast electron microscopes use a laser to generate pulsed electron beams. This technique dramatically improves a microscope’s ability to observe changes over time. In ultrafast microscopes, image quality isn’t based on a camera’s shutter speed but on the timing of the electron pulses.
The faster the pulse, the better the image.
Ultrafast electron microscopes operate by emitting pulses of electrons at speeds of a few attoseconds. At these speeds, pulses produce images similar to movie frames. However, scientists were still oblivious to the reactions and changes occurring in an electron as it evolves in real time between those frames.
Scientists created a single attosecond electron pulse by matching electron pulses. This improves the microscope‘s ability to capture rapid changes.
In 2023, scientists generated the first extreme ultraviolet radiation pulse so short it could be measured in attoseconds.
Based on this work, scientists developed a microscope in which a powerful laser is split and converted into two parts – a high-speed electron pulse and two ultra-short light pulses.
The first light pulse, the pump pulse, energizes the sample, making electrons move or change quickly. The second pulse, the “optical gating pulse,” acts like a gate, creating a tiny window of time to generate the attosecond electron pulse. The timing of this gating pulse determines the image resolution. By carefully syncing these two pulses, researchers can control when the electron pulses examine the sample to observe rapid processes at the atomic level.
Mohammed Hassan, associate professor of physics and optical sciences, said, “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 can attain attosecond temporal resolution with our electron transmission microscope – and we coined it ‘attomicroscopy.’ We can see pieces of the electron in motion for the first time.”
Journal Reference:
- Dandan Hui, Husain Alqattan et al. Attosecond electron microscopy and diffraction. Science Advances. DOI: 10.1126/sciadv.adp5805