Researchers used the European XFEL to produce ultrashort X-ray flashes that reached record intensity for this type of pulse.

To understand chemical reactions and perhaps one day control the electrons involved, scientists need a detailed picture of how electrons behave inside atoms and molecules. X-rays offer a way to probe that behavior, but the flashes can also change the sample they are meant to examine. Researchers therefore need enough light to gather useful information before those changes become substantial.

At the European XFEL, a team has now concentrated X-ray flashes onto an area roughly 100,000 times smaller than the cross-section of a typical human hair. The pulses lasted an estimated 300 attoseconds, with each attosecond equal to a billionth of a billionth of a second.