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Through photosynthesis, green plants and cyanobacteria are able to transfer sunlight energy to molecular reaction centers for conversion into chemical energy with nearly 100-percent efficiency. Speed is the key - the transfer of the solar energy takes place almost instantaneously so little energy is wasted as heat. How photosynthesis achieves this near instantaneous energy transfer is a long-standing mystery that may have finally been solved.


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Sunlight absorbed by bacteriochlorophyll (green) within the FMO protein (gray) generates a wavelike motion of excitation energy whose quantum mechanical properties can be mapped through the use of two-dimensional electronic spectroscopy. Image courtesy of Greg Engel, Lawrence Berkeley National Laboratory, Physical Biosciences Division


"We have obtained the first direct evidence that remarkably long-lived wavelike electronic quantum coherence plays an important part in energy transfer processes during photosynthesis,"




2-D electronic spectroscopy developed in the research group of Berkeley Lab’s Graham Fleming enables scientists to follow the flow of light-induced excitation energy through molecular complexes with femtosecond temporal resolution. In this 2-D electronic spectrum, the amplitude of the quantum beating signal for exciton 1 is plotted against population time. The black line covers the exciton 1 peak amplitude. The experimental data's agreement with theory is shown on the right. Credit: Lawrence Berkeley National Laboratory.


"By demonstrating that the energy transfer process does involve electronic coherence and that this coherence is much stronger than we would ever have expected, we have shown that the process can be much more efficient than the classical view could explain. However, we still don’t know to what degree photosynthesis benefits from these quantum effects."


Het is allemaal nog niet zo makkelijk, de wetenschap achter de natuur doorgronden