Scientists from the University of California, Berkeley discovered a new method to better understand the mechanics of sunlight-to-fuel conversion that will yield to safer and sustainable renewable fuels.

Plants grow through a complex photosynthetic process. The plants harvest the suns energy and store it in chemical bonds. Crucial to this process are antenna proteins, made up of light-absorbing pigments, which capture sunlight and transfer the energy to a reaction center where it kick-starts the building of sugars.

The researchers found that, when a pigment molecule absorbs light, one of its electrons is boosted into a higher energy state. When multiple pigments absorb light simultaneously, their excitation states may overlap and become linked, affecting the path of the energy transfer.

The researchers tested the mechanism by exciting a Fenna-Matthews-Olson protein, a well-studied photosynthetic antenna protein, with two different frequencies of laser-light. The researchers found that, when they used a third laser pulse to prompt the protein to release energy it emitted different frequencies than those it received, a sign that the two excitation states had linked.

While alternative methods for observing overlapping excitations have been proposed before, this new technique may be easier to implement since it relies only on frequency shifts and not on timed pulses.

According to the researchers, probing energy levels and pigment couplings in photosynthetic systems is essential to understanding, modeling and testing the function of these systems. With a better understanding of these systems, human engineers might one day be able to use the same energy conversion tactics that photosynthetic organisms use to develop safer and more sustainable renewable fuels.

The study was published in the American Institute of Physics' Journal or Chemical Physics. - K. D. Mariano
source: APEC-VC Korea