Researchers used the European XFEL to create X-ray flashes that were not only extremely short but also reached record intensity for this type of pulse. The researchers focused the X-rays to an area roughly 100,000 times smaller than the cross section of a typical human hair. This concentrated the X-ray light into a tiny but extremely powerful spot. The method could enable detailed studies of how electrons behave in atoms and molecules and, in the long term, could even allow researchers to control electrons during chemical reactions. The team has now published the results of the experiment, carried out in April 2026, in the journal Optica.

“This is a world record in intensity and fluence for a hard-X-ray attosecond pulse,” says Ichiro Inoue from the University of Tokyo, first author of the publication. Hard X-rays are light waves with a particularly short wavelength. Fluence measures how much energy this light delivers to a certain area. Intensity also takes into account how quickly that energy arrives.