Swiss X-ray free-electron laser (SwissFEL)

SwissFEL, at the Paul Scherrer Institut in Villigen, is Switzerland’s X-ray free-electron laser — a kilometre-long machine that fires ultrashort, laser-like pulses of X-rays bright enough to film atoms and molecules in motion.

Unlike a storage ring, a free-electron laser accelerates electrons in a straight line and sends them through long arrays of undulators, where they radiate coherently to produce pulses with the properties of laser light. SwissFEL’s X-ray pulses are far brighter than synchrotron light and only femtoseconds long — short enough to capture the fastest steps of chemical reactions and structural changes. SwissFEL achieved first lasing in December 2016 and ran its first time-resolved pilot experiment on the ARAMIS hard-X-ray beamline in 2017.

At a glanceFacility profile

Location

Villigen, Switzerland

Operator

Paul Scherrer Institut (PSI)

Type

X-ray free-electron laser

Energy

Up to 5.8 GeV

Beamlines

ARAMIS (hard X-rays) and ATHOS (soft X-rays)

First light

First lasing 2016

Website

psi.ch/swissfel

The scienceWhat researchers do here

SwissFEL is built for ultrafast science. Its intense, coherent femtosecond pulses let researchers make stop-motion movies of atoms and molecules as bonds break and form, follow electron and spin dynamics in materials, and determine the structures of proteins and other macromolecules by serial femtosecond crystallography — often capturing structural snapshots before radiation damage can set in. The science reaches across chemistry, biology, condensed-matter physics, energy materials and the environment.

Filming the invisible: SwissFEL’s femtosecond X-ray flashes are fast enough to freeze a chemical reaction in mid-step.