On January 15, 2025, the SuperSincrotrone free-electron laser (SS-FEL) generated its first isolated attosecond X-ray pulses — a milestone in ultrafast science that places the facility at the absolute frontier of time-resolved research.

Technical Achievement

The SS-FEL uses the chirped-pulse self-seeding scheme to produce transform-limited pulses as short as 180 attoseconds at a photon energy of 800 eV. Peak brightness exceeds 10³³ photons/s/mm²/mrad²/0.1%BW — nine orders of magnitude beyond the storage ring source.

First user experiments will begin in Q3 2025, targeting charge migration dynamics in amino acids, ultrafast magnetization reversal, and core-hole decay processes that have never been observed in real time.