Break Through the Limit of Optical Microscope And See Electrons in Crystal Atoms
Discovery of a New Optical Microscope
Visible light optical microscopes allow scientists to see tiny objects such as living cells. However, visible light microscopes cannot distinguish how electrons are distributed among atoms in a solid. Now, Professor Eleftherios Goulielmakis of the Extreme Photonics Laboratory of the University of Rostock and the Max Planck Institute for Quantum Optics has developed a new optical microscope called Piccope.
The researchers used powerful laser flash lamps to illuminate the thin film of crystal material. These laser pulses drive the crystal electrons into a fast swinging motion. When the electrons bounce off the surrounding electrons, they emit radiation in the extreme ultraviolet part of the spectrum. By analyzing the characteristics of this radiation, the researchers synthesized some pictures showing how the electron cloud is distributed among the atoms in the solid crystal lattice, with a resolution of tens of picometers. These experiments paved the way for a new class of laser-based microscopes.
This microscope allows physicists, chemists, and materials scientists to peek into the details of the microscopic world with unprecedented resolution, and to understand and ultimately control the chemical and electronic properties of materials. For decades, scientists have used lasers to understand the inner workings of the microscopic world. Such laser flashes can now track ultrafast microscopic processes inside solids. Nevertheless, it is still impossible to decompose electrons in space.
Ernst Abbe discovered the cause more than a century ago. Visible light can only distinguish objects whose size is commensurate with its wavelength. The wavelength is about a few hundred nanometers, which is the Abbe limit. But to see electrons, the microscope must increase its magnification several thousand times. To overcome this limitation, the researchers developed a microscope that can work with powerful laser pulses that can force electrons inside crystal materials to become photographers in the space around them.
When the laser pulse penetrates the inside of the crystal, it can grab an electron and drive it to swing quickly. When the electron moves, it feels the surrounding space. When the laser-driven electron passes through the bumps caused by other electrons or atoms, it slows down and emits radiation at a much higher frequency than the laser. Hee-yong Kim, a doctoral researcher at the Extreme Photonics Laboratory, said: By recording and analyzing the characteristics of this radiation, the shape of these tiny bumps can be inferred, and pictures can be drawn that show the high or low electron density in the crystal.
The Future of Laser Microscopes
The laser Pythian microscope combines the ability to look at most substances (such as X-rays) and the ability to detect valence electrons. The latter can be achieved by scanning tunneling microscopes, but only on the surface. Meng Sheng, a theoretical solid-state physicist from the Institute of Physics, Chinese Academy of Sciences in Beijing, is a theoretical solid-state physicist in the research team. He said: With a microscope capable of detecting the valence electron density, we may soon be able to Calculating the performance of solid-state physics tools for benchmarking can optimize modern and state-of-the-art models to predict the properties of materials with finer details.
This is an exciting aspect brought about by laser microelectron microscopy. Now, researchers are further developing this technology, planning to detect three-dimensional electrons, and further use a wide range of materials including two-dimensional and topological materials.