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Thesis
Home   /   Thesis   /   Role of excited state vibrational modes of chlorophylls in photosynthesis

Role of excited state vibrational modes of chlorophylls in photosynthesis

Life Sciences Molecular biophysics

Abstract

Photosynthesis empowers the entire biosphere and is arguably the most important biological process on earth. The quantum efficiency of excitation energy transfer (EET) in photosynthetic light-harvesting complexes can reach almost unity. This high efficiency is even more puzzling if we take into account that the high excitation energy transfer through hundreds of pigments in a disordered energetic landscape cannot be explained with the current models. Currently, there are two main hypotheses to explain the ultrafast energy transfer: “quantumness” and “vibrational assistance” (see context section). To validate these hypotheses, it is necessary to characterize the electronic and vibrational properties of the excited states of the cofactors involved in the ETT process. We have designed an interdisciplinary project, in which the student will be trained in biochemical techniques for protein purification and ultrafast photophysics techniques to analisys of the excitation energy transfer. The use of different detergents for purifying light-harvesting complexes leads to disturbed systems with differences in the excitation energy pathways. The differences between light-harvesting complexes from each purification will be characterized by resonance Raman and time-resolved fluorescence. Then, we will use ultrafast techniques such as fs-transient absorption, 2-D electronic spectroscopy (2DES) and femtosecond stimulated Raman Spectroscopy (FSRS). This data will be employed to develop new models for photosynthetic energy transfer. The student will be involved in the analysis and discussions for the theoretical modeling of this process but learning modeling techniques is out of the scope of the thesis.

Laboratory

Institut des sciences du vivant Frédéric JOLIOT
SB2SM - Service de Bioénergétique, Biologie Stucturale, et Mécanismes
Laboratoire Bioénergétique, Métalloprotéines et Stress
Paris-Saclay
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