Scientists at the Paul Scherrer Institute PSI have, for the first time, demonstrated a technique that synchronizes ultrashort X-ray pulses at the X-ray free-electron laser SwissFEL. This achievement opens new possibilities for observing ultrafast atomic and molecular processes with attosecond precision.
Scrutinizing fast atomic and molecular processes in action requires bright and short X-ray pulses—a task in which free-electron lasers such as SwissFEL excel. However, within these X-ray pulses the light is internally disordered: its temporal structure is randomly distributed and varies from shot to shot. This limits the accuracy of certain experiments.
To tame this inherent randomness, a team of PSI researchers has succeeded in implementing a technique known as mode-locking to generate trains of pulses that are coherent in time. “We can now obtain fully ordered pulses in time and frequency in a very controlled manner,” says accelerator physicist Eduard Prat, who led the study, published in Physical Review Letters.
