How we use crazy-fast laser pulses to study electrons
Using invisible light to explore the invisible building blocks of everything sounds like magic. But it is, in fact, the atomic physics being advanced every day in a lab off Woodruff Avenue on our Columbus campus.
The Agostini-DiMauro Research Group has spent a decade building the Quantum Trajectory Selector, the next step in the electron investigation techniques developed by the three winners of the 2023 Nobel Prize in Physics. The trio includes Ohio State Professor Emeritus Pierre Agostini.
Learn more by watching the motion graphic video above.
Want to dig deeper into Ohio State researchers’ groundbreaking study of electrons? Here are some basics about how the process works.
Electrons
Atoms make up all matter — everything from a pencil to your body. There are a million times more atoms inside you than there are stars in the visible universe.
Electrons are among the particles that make up atoms. The other particles — protons and neutrons — form a nucleus that attracts the electrons, which constantly zip around the nucleus at 1,400 miles per second. To “see” them move, you need incredibly short shutter speeds.
Attoseconds
One attosecond is a billionth of a billionth of a second. To put that in perspective, there are as many attoseconds in one second as there have been seconds since the universe began 13.8 billion years ago. Before attosecond work became a possibility, tracking electrons was impossible.
Harmonics and attosecond light pulses
Within a vacuum system, a laser shot into gas or liquid (the argon gas in the video above) nudges the electrons and gets them excited enough to jump away from their nucleus. Freed, the electrons are pulled back and forth by the laser pulse. Gaining energy, they may recollide with the nucleus. To return, they shed the extra energy in a pulse of ultraviolet light.
Those light waves combine with the laser’s waves, speeding up its light pulses. These days, they can be as short as a few dozen attoseconds. In 2001, Agostini figured out that by splitting the laser in two (as illustrated in the video) and exposing just one part to the harmonics (the juicing-up of the laser), it became possible to measure the quickened pulses — the super-short shutter speeds.
The result
Electrons still move faster than we can clock them, so the resulting “photo” is blurred — similar to how an old camera would capture spinning helicopter blades or hummingbird wings. But the experiments let us interpret the dynamics at play.
This knowledge could lead to more powerful supercomputers and circuitry, new approaches to medicines and better medical diagnoses, given that the atoms of each element leave a unique fingerprint in the experiments.
