The next big hit in molecule Hollywood.

in space, with atoms moving about in a stately dance. They spin the structures mentally to examine them from all angles, perhaps twisting each molecule until a bond pops open and another snaps into place. Such movies play inside the minds of most chemists because they offer a way to visualize how reactions happen. “The unifying thought experiment across all disciplines of chemistry is to imagine atoms moving in real time,” says Dwayne Miller, a physical chemist at the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the University of Toronto in Canada. “This is a dream the entire field has.” Chemists have been dreaming like this for more than 150 years, ever since the idea of molecular structure was first conceived. But now these fantasies are becoming a reality. Researchers are directing molecular movies in the lab using a range of techniques, most of which illuminate the scene with incredibly brief pulses of light or electrons. Some rely on the atomic precision of scanning tunnelling microscopes (STMs), whereas others use intense bursts of X-rays to reveal their target’s structure. Their goal is to film events that take place in picoseconds (ps, 10 s) or femtoseconds (fs, 10 s), with atoms moving mere picometres (a hydrogen atom is roughly 100 pm in diameter). At this resolution, researchers can for the first time directly observe a molecule writhing in slow motion, atomic bonds vibrating and breaking, or even THE NEXT BIG HIT IN MOLECULE HOLLYWOOD