Photosynthesis is the process by which plants convert sunlight into energy, and it relies on an extremely efficient energy transfer system. Before it can be converted into chemical energy, the light energy must first be captured and transmitted, a process that occurs almost instantaneously and with minimal energy loss. A new study from the Chair of Dynamic Spectroscopy at the Technical University of Munich (TUM) reveals that quantum mechanical effects play a crucial role in this energy transfer process.
Through precise measurements and simulations, a research team led by Professors Erika Keil and Jürgen Hauer revealed how these quantum effects increase the efficiency of photosynthesis.
Efficiently harnessing solar energy and storing it as chemical energy has long been a challenge for engineers. However, nature solved this problem billions of years ago. A new study shows that quantum mechanics is not just a concept for physicists, but also plays a crucial role in biological processes.
Green plants and other photosynthetic organisms use quantum mechanics to capture and transmit sunlight with extraordinary efficiency. As Professor Jürgen-Hauer explains: "When light is absorbed by a leaf, for example, the electron excitation energy is distributed over multiple states of each excited chlorophyll molecule; this is called excited state superposition. This is the first stage of an almost lossless transfer of energy within and between molecules, making possible the efficient forward transmission of solar energy. Quantum mechanics is therefore crucial for understanding the first steps in energy transfer and charge separation".
The energy transfer process of chlorophyll, which cannot be satisfactorily understood by classical physics alone, occurs continuously in green plants and other photosynthetic organisms (such as photosynthetic bacteria). However, the exact mechanism remains incompletely elucidated. Hall and first author Erica Kyle believe their study lays important new groundwork for elucidating how chlorophyll, the pigment in chlorophyll, works.
Applying these findings to the design of artificial photosynthesis devices could help harness solar energy to generate electricity or conduct photochemical research with unprecedented efficiency.
In this study, the researchers looked at two specific spectral segments where chlorophyll absorbs light: the low-energy Q region (yellow to red spectral range) and the high-energy B region (blue to green spectral range). The Q-region consists of two different electronic states coupled by quantum mechanics. This coupling leads to lossless energy transfer in the molecule. The system then relaxes by "cooling" (i.e. releasing energy in the form of heat). This study shows that quantum mechanical effects can have a decisive influence on biologically relevant processes.
Compiled from /ScitechDaily