The microscopic world of atoms and electrons is still shrouded in mystery. Not just because it's tiny in physical scale, but also because everything that happens down there happens incredibly fast. To better understand molecular events, scientists use short-pulse X-ray lasers to freeze moments in time with precise snapshots. Now, researchers at ETH Zurich have managed to shorten the pulse of an X-ray laser down to 43 attoseconds – which the team says is the shortest controlled event ever created by humankind.
For reference, an attosecond is one quintillionth of a second. If we scale that up, there are as many attoseconds in one second as there are seconds in 31.7 billion years. It's a mind-bogglingly small time frame, is what we're trying to say.
Other X-ray lasers, like the Linac Coherent Light Source, use pulses on the scale of femtoseconds – that's fast enough to capture the vibrations of atoms, but it's about 1,000 times longer than the ETH Zurich pulse. The new record of 43 attoseconds just edges out a previous achievement, where a University of Central Florida team generated a pulse of 67 attoseconds.
The researchers used an infrared laser to generate a soft X-ray laser pulse with a large spectral bandwidth. With pulses this precise, the ETH team can image the movement of electrons, which occurs in the range of attoseconds. The researchers were able to peer inside elements like phosphorus and sulfur with incredibly high "time resolution," exciting the electrons in the deepest part of those atoms.
By shrinking the scale of laser spectroscopy down to mere attoseconds, the researchers say that the movements of atoms and electrons during chemical reactions can be more closely tracked. This precision could, for example, allow scientists to watch step-by-step how sunlight excites electrons in a photovoltaic cell to generate electricity, and that data can then be used to develop more efficient solar power systems.
Beyond observation, attosecond spectroscopy can be used to actually intervene in chemical reactions that normally happen far too fast, and even break chemical bonds. To help with that kind of study, the researchers are currently working on making those laser pulses even shorter.
The study was published in the journal Optics Express.
Source: ETH Zurich