UNL physicist Centurion earns DOE early career research grant

It's well known that sunlight fuels plants. But exactly how plants convert photons of light into energy is a mystery.

The first molecular step in conversion takes less than one-trillionth of a second, far too fast for scientists to see the process. Unlocking the mystery could lead to better green energy sources.

Martin Centurion, an assistant professor of physics at the University of Nebraska-Lincoln, has discovered a way to peer into that ultra-fast molecular world, and the Department of Energy has given him a prestigious Early Career Research Program award of $750,000 to support his research. Only 4 percent of applicants received the award, which is funded by the American Recovery and Reinvestment Act.

When a photon of light hits a molecule on a plant's leaf or in a human eye, for example, the molecule undergoes structural changes to turn that photon energy into chemical energy. For a plant, that energy becomes fuel for growth and reproduction. Eyesight depends on the converted energy traveling to the brain.

Being able to see those structural changes would provide insight into the molecule's function.

"This could help to get a better understanding of how to convert energy light from the sun into chemical energy," said Centurion, and that might help scientists develop alternative energy sources.

To see a structural change that lasts just one-trillionth of a second, Centurion hits gas molecules with a laser pulse, a source of photon energy, to start the molecular change. The laser also triggers a burst of electrons. When the electrons hit the molecules, they scatter. By analyzing the electron scatter, Centurion can recreate the molecule's structure at that moment, like taking its picture.

By lengthening the timing between the laser pulse and the electron snapshot, Centurion can create a movie of the changes occurring in the molecular structure.

The award will allow Centurion to hire two graduate students or technicians and to purchase more powerful equipment. It also positions the new UNL faculty member well for the future.

"It's really providing the resources to carry out the project," said Centurion. "It allows me to be more ambitious with the goals."