Scientists generate record-breaking X-ray pulses with peak intensity of 10^20 W/cm²

By combining hard X-ray attosecond pulses from the European XFEL with total-reflection focusing X-ray optics, researchers have generated nanofocused hard X-ray attosecond pulses with intensities and fluences comparable to the highest values attained in the hard X-ray regime. A peak intensity on the order of 10$^{20}$ W/cm$^2$ was confirmed through the observation of saturation in amplified spontaneous emission from copper atoms. These X-ray pulses enable new scientific opportunities, including the exploration of higher-order nonlinear light–matter interactions, damage-free structure determination, and coherent control of atoms and molecules.

Record-Breaking Intensity

The experiment took place in April 2026, where the team concentrated X-ray flashes into an area roughly 100,000 times smaller than the cross-section of a typical human hair. Each X-ray pulse lasted an estimated 300 attoseconds, providing a way to investigate events that unfold too quickly for conventional observation. The advanced Kirkpatrick-Baez optical system used in the experiment consisted of two precise mirrors that focused the beam in different directions, achieving a focal spot measuring just 180 × 330 nanometers.

New Scientific Opportunities

To confirm the exceptional intensity of their X-ray pulses, the researchers directed them at a thin sheet of copper. The focused flashes reached peak intensities exceeding 10²⁰ watts per square centimeter, demonstrating amplified spontaneous emission. This phenomenon occurs when incoming X-rays stimulate other excited copper atoms to release additional X-rays in the same direction, producing an amplified beam. The findings, published in the journal Optica, could significantly expand scientists' ability to investigate some of nature's fastest processes, particularly the behavior of electrons during chemical reactions.