Atoms and molecules move far too fast for the human eye and most of our instruments to see clearly, meaning much of what happens down at that scale is shrouded in mystery. To get a better look we need a "camera" that's several kilometers long, and one such facility is firing up this month. The European X-ray Free Electron Laser (XFEL), which happens to be the largest x-ray laser in the world, can take 3,000 images per second of that tiny world.
To snap these high-resolution X-ray images, the European XFEL first accelerates electrons down a mile-long (1.7 km) tunnel. Once they're traveling at close to the speed of light, they pass by magnets, which cause the electrons to start to wobble, and as they do they throw off pulses of high-energy X-rays. The scientists will have placed a sample of what they want imaged in a certain spot beforehand, and these X-rays will strike that sample, scattering photons that create an X-ray image of the material's atomic structure.
Compared to other high-powered X-ray lasers, the European XFEL has one unique feature to its name. It can fire off 27,000 pulses per second, making it about 200 times faster than the Linac Coherent Light Source (LCLS) in the US. That means it can take 3,000 individual images per second, allowing scientists to study the structure of smaller individual particles than is possible at other facilities, and create movies capturing the movements of enzymes, viruses and chemical reactions.
"It's such a different beast to anything else on the planet that it really feels like going into uncharted territory," says Arwen Pearson, a researcher at the Centre for Free-Electron Laser Science in Hamburg, Germany.
The European XFEL was taken for its first test run back in May, but that was at the far, far slower pace of just one pulse per second. Later in September, the facility will be brought up to its full speed of 27,000 pulses per second, but it won't hold that fire-rate record for long: work has begun on an upgrade for the LCLS that will see it blasting up to a million pulses per second when it comes online in the early 2020s.