If action flicks seem to be getting faster these days, just wait. This year, laser physicists succeeded in making the first-ever movies in which individual frames were measured in attoseconds, or billionths of a billionth of a second. The new high-speed filmmaking techniques are expected to spawn a new genre of cinema devoted to tracking the motion of electrons around atoms.
Laser physicists have been refining their high-speed moviemaking approaches for years. But most rely on the same basic principle, using ultrashort pulses of laser light, like bursts from a strobe light, to freeze motion in flight. Researchers now routinely use the technique to capture the blur of molecules as they break and weld bonds in a chemical reaction, events that take place on the order of 1 to 100 femtoseconds, or 10-15 seconds.
Dutch and French researchers broke the attosecond barrier last year, when they trained ultrashort laser pulses on a gas of argon atoms, which in turn emitted a train of pulses, each lasting just 220 attoseconds. A team of Austrian, Canadian, and German researchers followed hard on their heels with a related technique that turned out individual 650-attosecond pulses, which are more easily used as moviemaking strobes.
This year, researchers turned their new attosecond strobes onto the action within atoms. In October, an Austrian-German team used attosecond pulses to excite electrons in krypton atoms, each of which left behind an electron vacancy. With another laser pulse, they were then able to track the timing with which excited electrons gave up some of their energy and fell back into the more stable energy levels. It's not Hitchcock. But then again, attosecond movies will give physicists a whole new view of life inside the atom.