Tucson Standard

Researchers at the University of Arizona have developed what they describe as the world's fastest electron microscope, capable of capturing freeze-frame images of moving electrons. This advancement is expected to significantly impact fields such as physics, chemistry, bioengineering, and materials sciences.

"When you get the latest version of a smartphone, it comes with a better camera," said Mohammed Hassan, associate professor of physics and optical sciences. "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."

Hassan led a team that published their findings in Science Advances under the title "Attosecond electron microscopy and diffraction." The team included Nikolay Golubev, assistant professor of physics; Dandan Hui, co-lead author and former research associate now at Xi'an Institute of Optics and Precision Mechanics; Husain Alqattan, co-lead author and assistant professor at Kuwait University; and Mohamed Sennary, a graduate student.

A transmission electron microscope magnifies objects up to millions of times using beams of electrons instead of visible light. Ultrafast versions use lasers to generate pulsed beams for enhanced temporal resolution.

The 'attomicroscope' developed by U of A researchers consists of two sections: one converting ultraviolet pulses into ultra-fast electrons inside the microscope, while another uses lasers to control electron movement within samples.

Previous ultrafast microscopes emitted trains of attosecond-long pulses but missed reactions occurring between frames. The U of A team generated single attosecond pulses for improved temporal resolution.

Their work builds on Nobel Prize-winning research by Pierre Agostini, Ferenc Krausz, and Anne L’Huilliere in 2023. Using these principles, U of A researchers split a laser into fast electron pulses and ultrashort light pulses for energy input (pump pulse) and timing control (optical gating pulse). Synchronizing these pulses allowed them to observe atomic-level processes.

"The improvement of the temporal resolution inside electron microscopes has been long anticipated," Hassan said. "But now...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."

---