Researchers produced high-power attosecond hard X-ray pulses at megahertz repetition

Since the discovery of X-rays in 1895, scientists have continuously endeavored to increase the brilliance of X-ray sources to facilitate X-ray techniques. Ångstrom and attosecond are critical spatiotemporal scales for studying electron dynamics in materials. While attosecond pulses, with wavelengths on the order of atomic scales, are anticipated to be vital in advancing attosecond science, generating high-power hard X-ray attosecond pulses at Ångstrom wavelengths is still a significant challenge.

The difficulty lies in the need for precise control over these pulses’ temporal and spatial characteristics, which is necessary for exploring electron behavior at such small scales. A European XFEL and DESY research team have made a breakthrough in X-ray science by generating high-power attosecond hard X-ray pulses at megahertz repetition rates. These pulses, with energies over 100 microjoules and durations of a few hundred attoseconds, enable new studies of ultrafast electron dynamics and atomic-level non-destructive measurements.



Jiawei Yan, physicist at European XFEL and lead author of the study published in Nature Photonics, said, “With these unique X-rays, we can perform damage-free measurements of structural and electronic properties. This paves the way for advanced studies like attosecond crystallography, allowing us to observe electronic dynamics in real space.” Traditional methods for generating ultra-short hard X-ray pulses required reducing the electron bunch charge, which limited pulse energy.

The research team at European XFEL overcame this by developing a self-chirping method, utilizing electron beam collective effects and specialized transport systems. This approach generates attosecond X-ray pulses with terawatt-scale peak power and megahertz repetition rates without reducing the electron bunch charge, enabling high-energy, ultra-fast X-ray pulses for broader practical applications. Gianluca Geloni, group leader of the FEL physics group at the European XFEL, said , “By combining ultra-short pulses with megahertz repetition rates, we can now collect data much faster and observe processes that were previously hidden from view.

This development promises to transform research across multiple scientific fields, especially for atomic-scale imaging of protein molecules and materials and investigating nonlinear X-ray phenomena.” Journal Reference:.