Leonato Nchinda

Leonato Nchinda

PhD Student

University of Pretoria

Photosynthesis, an indispensable process, is the most important biological process on earth. By liberating oxygen and consuming carbon dioxide, it has transformed the world into the hospitable environment we have today. The light-harvesting protein complexes of photosynthetic organisms are intriguing molecular machines. They use the principles of quantum mechanics and switch between light-harvesting and photoprotective functions. The photoprotective state is established through a complex mechanism known as non-photochemical quenching (NPQ) during which excitation energy is thermally dissipated in a clean and safe manner. Since the photosynthetic light-harvesting process is dominated by the laws of quantum mechanics, precise control of the switch between light-harvesting and NPQ demands a technique based on quantum control; an approach that has not yet been utilised. In this light, I am using laser coherent control to observe and actively manipulate the course of physical and chemical processes immediately after photoexcitation of LHCII, the main light-harvesting complex of plants. Through the wavefront shaping of ultrashort laser pulses under the instruction of a genetic algorithm, the quenching process can be optimised or minimised. The 4f setup, which forms part of an ultrafast transient absorption spectroscopy setup, contains a Spatial Light Modulator (SLM), which will be used for shaping the pump pulse in phase and amplitude, while a genetic algorithm will be implemented to manipulate the laser pulses until an optimal pulse shape is achieved. At the end of this interesting adventure, we believe that the results obtained will be able to guide agricultural biotechnologies to develop high-light tolerant crops through genetic modification. Finally, with the advent of Biomimicry, a perfect understanding of the fundamental properties of these intriguing molecular machines (like LHCII), will serve as a great inspiration for finding green, sustainable energy solutions for our planet.