Quantum tricks turn leaves into perfect solar panels, scientists unravel how
A new study is shining fresh light on how green plants and other photosynthetic organisms transport solar energy so efficiently. The latest research also highlights the importance of quantum mechanics in enabling an almost loss-free movement of energy from light absorption to storage in the form of chemical energy.
This a phenomenon that engineers have tried to replicate for decades to harness clean energy.
According to Prof. Jürgen Hauer, one of the study’s authors, “When light is absorbed in a leaf, for example, the electronic excitation energy is distributed over several states of each excited chlorophyll molecule; this is called a superposition of excited states.”
“It is the first stage of an almost loss-free energy transfer within and between the molecules and makes the efficient onward transport of solar energy possible. Quantum mechanics is therefore central to understanding the first steps of energy transfer and charge separation.”
Understanding quantum tricks used by nature’s near-perfect light harvester
Plants and photosynthetic bacteria have long demonstrated efficiency in energy conversion that conventional physics struggles to explain fully. The study sets out to clarify what makes chlorophyll, the pigment giving leaves their green color, such a powerful light harvester.
Hauer and first author Erika Keil say the findings add a vital piece to the puzzle of exactly how energy transfer occurs at the quantum level, knowledge that could, in theory, help researchers develop artificial photosynthesis units to exploit solar energy with unprecedented efficiency.
Focusing on two sections of the chlorophyll absorption spectrum, the researchers examined both the low-energy Q region (yellow to red range) and the high-energy B region (blue to green). In the Q region, two closely related electronic states are quantum mechanically coupled, an interaction that plays a key part in the virtually loss-free transfer of energy.
The excited system subsequently relaxes by releasing heat. According to the authors, this “cooling” step is a crucial transition from an energized state to a lower energy state without wasteful energy losses.
Examining the loss-free energy transfer pathway
The study’s abstract details how the team combined polarization-controlled static and ultrafast optical spectroscopies to observe these processes in chlorophyll a. They supported the experiments with computational models and found that energy flows within a timescale of around 100 femtoseconds (a femtosecond is one quadrillionth of a second).
While one key intermediary state (Qx) exists fleetingly on a timescale under 30 femtoseconds, the team concludes that its brief presence is essential to bridging the energy between the B and Q regions. The overall process unfolds so smoothly that it offers an almost loss-free pathway for energy transport.
As Hauer notes, nature has “found a perfect solution” to transforming solar input into chemical energy. Understanding the intricate interplay of quantum states in chlorophyll could help scientists engineer similarly efficient electricity generation or photochemistry methods.
Research into these mechanisms remains ongoing, but the authors see these results as a significant step toward replicating nature’s feats, potentially opening the door to more efficient renewable energy solutions. By shedding light on how plants operate at a subatomic level, this study may guide future innovations in capturing the sun’s power.
Source: Interesting Engineering
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Quantum tricks turn leaves into perfect solar panels, scientists unravel how