Dynamics of energy transfer in light harvesting photosynthetic systems

Abstract

Photosynthesis is the process by which plants, algae and photo synthetic bacteria convert sunlight energy into chemical energy (ATP). The initial stages of this process (harvesting solar energy and transferring it to the reaction centres) occur extremely fast and with an efficiency of close to 100%. Studying the dynamics of these reactions will enable us to develop artificial functional light harvesting arrays and energy transfer systems that mimic the process in nature, thus helping us use light as an energy source that is environmentally clean, efficient, sustainable and carbon-neutral. These reactions can be measured using femtosecond pump-probe spectroscopy (transient absorption in the liquid phase and monitoring the subsequent kinetics in the wavelength region: 400 nm-700 nm). In order to perform these experiments, photo synthetic pigment-protein complexes must be isolated, purified and characterised. In this work, these photo synthetic complexes were isolated from spinach leaves and characterised using various biological and spectroscopic techniques. Finally, the first results of pump-probe application to biological samples in South Africa were discussed.