Taking Snapshots Down to the Atomic Level

The mile-long machine produces a laser beam made of X-rays instead of visible light. Its laser bursts are so bright and so brief that researchers will use them as an ultrafast stop-motion camera to capture the minute details of things previously unseen, such as the arrangement of atoms in metals, semiconductors, ceramics, polymers and proteins.

The laser is expected to have wide-ranging impacts on medicine, advanced energy research and other fields.

Until now, watching atoms as they formed or broke molecular bonds was essentially observing a blur. "You can see the beginning state, you can see the end state and then something happens in the middle and it's a blur," John Galayda, SLAC's director of construction for the laser, said. But the high resolution provided by the X-ray laser will allow researchers to compile a series of snapshots of molecules as they change shape during reactions, and then string those images together to create a never-seen-before movie.

The LCLS creates its laser by accelerating a beam of electrons through a series of magnets in a room known as the Undulator Hall. The alternating magnetic field created by the magnets causes the electron beam to wiggle from side to side as it passes by. As the electrons change course, some of their energy is converted to X-rays, which are organized into a coherent laser beam.

When the laser was tested inside its tunnel last week, it worked on the second attempt, sooner than many of the participants gathered in the control room expected.

COMPAMED.de; Source: Stanford University