University of Tokyo researchers have established a high-frequency laser source facility located at the university that enables investigation of time-dependent phenomena such as ultrafast chemical reactions and fast-acting biological processes. The facility specifically allows scientists to produce coherent extreme ultraviolet (XUV) pulses and x-ray pulses — both highly precise light forms with finely controlled parameters crucial to many experiments. The coherent XUV light source is particularly adept at revealing clear details of biological and physical samples. Whereas existing facilities for research and investigation using these pulses require large particle accelerators and are often prohibitive to researchers, the new facility promises access for a broad range of scientists. The XUV source facility is located in an underground laboratory, and contains a 5- × 2-m vacuum container housing a 100-m-long resonator, which stores laser light. Two distinct pockets of gases capable of altering the characteristics of the passing laser are located on the coil. When the laser and gases interact, a process known as high-order harmonic generation occurs. The process ensures that the XUV source delivers ultrashort pulses, useful for probing fast phenomena, as well as high frequencies, for examining the structure and chemical makeup of matter. A schematic shows how two distinct beam sources are generated in the University of Tokyo facility. Courtesy of Springer Nature. The presence of the gases also results in two separate beams of XUV and soft x-ray light, which researchers cast onto samples during investigation. High-speed imaging sensors finally read the light that is reflected off the samples. Established XUV facilities using synchrotron radiation pulses also in the megahertz region have long bursts that are poorly suited for resolving dynamic, fast-acting phenomena. The new facility and its approach involve extremely short XUV pulses occurring at extremely high frequencies — in the megahertz region, or million of cycles per second, said Katsumi Midorikawa, professor in the University of Tokyo Institute for Photon Science and Technology and RIKEN Center for Advanced Photonics. “Facilities to produce coherent XUV and soft x-rays are huge machines based on particle accelerators – like smaller versions of the Large Hadron Collider in Europe,” Midorikawa said. “Given the rarity of these facilities and the expense on running experiments there, it presents a barrier to many who might wish to use them. This is what prompted myself and colleagues at UTokyo and RIKEN to create a new kind of facility that we hope will be far more accessible for a greater number of researchers to use.”