Electrons are corralled to create an X-ray laser that snaps shots in just ten quadrillionths of a second.

An accelerator has generated brief X-ray bursts three times more powerful than any other such pulse, in an advance that promises to deliver sharper images of biological molecules and chemical structures.

Only a few sites in the world produce X-ray free-electron-laser pulses, which are created by coaxing bunches of electrons into swerving back and forth. This motion forces them to emit bright bursts of X-rays. Marc Guetg and his colleagues at the SLAC National Accelerator Laboratory in Menlo Park, California, devised techniques to pack electrons closely together just before they emit the X-rays, overcoming the electrons’ tendency to repel each other.

The resulting laser pulses last for only ten quadrillionths of a second and are the brightest ever produced. Such powerful flashes can image objects such as individual viruses with very high spatial resolution. The briefness of the pulse means that scientists can capture the atomic structure of a target before the pulse damages it, the authors say.