The FXE instrument at the European XFEL

The FXE instrument at the European XFEL is designed to analyse chemical processes that are otherwise too fast to observe. Short pulses of laser-like X-rays, which can pick up atomic details, give scientists deeper insight into the rapid changes in molecules during an ongoing reaction. Samples are dissolved in a liquid jet. The molecules are energised with an optical laser, shown in red, which initiates a chemical reaction. With the European XFEL’s 27 000 intense X-ray pulses per second, shown in blue, the instrument can record snapshots from the reacting molecules in steps of a millionth of a billionth of a second, or a femtosecond. Thanks to the high repetition rate, scientists can collect vast amounts of superior-quality data from the reacting system. Once put in temporal sequence, the data can deliver an ultra-slow–motion molecular movie, helping to better understand chemical processes such as catalysis and enzymatic action.