Peering into Ultra-fast Molecular World |
It’s well known that sunlight fuels plants. But exactly how plants convert photons of light into energy is unknown. Unlocking the mystery could lead to better green energy sources.
The first molecular step in conversion takes less than one-trillionth of a second, far too fast for scientists to see the process. But UNL physicist Martin Centurion has discovered a way to peer into that ultra-fast molecular world.
"This could help to get a better understanding of how to convert energy light from the sun into chemical energy," said Centurion, who received a $600,000 Early Career Research Program award from the Department of Energy to support his work.
When a photon of light hits a molecule, whether 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.
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 a 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. Being able to see those structural changes will provide insight into the molecule’s function.
Understanding how the molecule converts energy may one day help scientists develop alternative energy sources.