The process of photosynthesis allows some bacteria and plants to convert carbon dioxide, water and sunlight into its own food as well as convert these into oxygen for animals—and this has remained a great mystery for scientists all over the world.
Reason why biophysics researchers from the University of Michigan (U-M) further dug their hands into the mystery, to understand what is considered Earth’s most essential biochemical process.
The researchers applied short light pulses to look into the mechanics of the process and to clarify the real role of molecule vibrations in the process of energy conversion, which supports life on Earth. Their findings identified particular molecular vibrations, which assist in charge separation or the process of getting rid of electrons from atoms during the initial process of photosynthesis.
"Both biological and artificial photosynthetic systems take absorbed light and convert it to charge separation," study’s lead author Jennifer Ogilvie says in a statement.
For natural photosynthesis, charge separation brings about biochemical energy. For artificial systems, the researchers would like to use charge separation to produce electricity or another usable energy source such as biofuel.
Ogilvie, who is also an associate professor of biophysics and physics at the U-M, and her team collaborated with U-M professor emeritus Charles Yocum of the Department of Chemistry and the Department of Molecular, Cellular and Developmental Biology to remove what is called the leaves’ photosystem II reaction centers. Photosystem II is a group of pigments and proteins and the sole natural enzyme known to use solar energy to divide water into oxygen and hydrogen.
A bag of spinach leaves with removed veins and stems was used as sample. They placed the leaves in a blender and went ahead with a number of extraction steps to slowly take out protein complexes from its membrane but at the same time keep it intact.
Ogilvie says this specific system interests them greatly because the process of charge separation occurs "extremely efficiently."
After stimulating the photosystem II and scrutinizing the produced signals, the researchers were able to gather insights on routes taken by the charge and energy into the leaves, which provide them a good track of what’s going on, where the energy transfers and time the charge separation occurs.
According to Ogilvie, they discovered that there is an improved charge separation when the energy level gaps are "close to vibrational frequencies."
The study’s findings could possibly assist engineers in developing more effective solar cells and energy storage systems, as well as possibly suggest new evidence as to how photosynthesis can manage to be so useful, according to researchers.
The research paper, "Vibronic Coherence in Oxygenic Photosynthesis," appears in Nature Chemistry journal online.
