Research objectives and content
The objective of this project is to solve the problem of the electronic structure of the light-harvesting complex of the photosynthetic bacterium Rhodopseudomonas acidophila. The three-dimensional geometric structure of this complex has recently been solved and it appears that it contains 27 bacteriochorophyll molecules in a highly symmetric circular arrangement. The strong interactions between the molecules give rise to spatially delocalised, optically excited states which are known as Frenkel excitons and which determine both the spectroscopic properties of the complex and the transfer mechanism of the excitation energy to the reaction center where the charge separation, the primary step of the photosynthesis takes place.
So far it has not been possible to study the electronic structure of this complex as the optical transition of the 27 possible exciton states are hidden within an absorption band which is dominated by strong inhomogeneous broadening resulting from variations in the local environment of individual pigments. To solve this problem, I propose to use the recently developed confocal and near-field optical techniques to perform spectroscopic measurements on individual complexes at cryogenic temperatures. The method will allow us to resolve the transitions associated with the 27 exciton states and to obtain information essential for a full understanding of the intrinsic photophysical properties of this complex and of the energy transfer mechanism in the primary step of photosynthesis.
Training content (objective, benefit and expected impact)
This project will allow me to gain international experience in scientific research by working directly with two groups which have been in the forefront of molecular physics and biophysics, and profit from the achievement and knowledge of specialists in the broad, diverse range of experimental methods. At the same time, I plan to expand the application of confocal and near-field optical spectroscopic techniques which I am developing in Bordeaux during my thesis, into the area of photosynthesis research, a very novel development. I will actively seek scientific training by participation in local seminars and stud programs, as well as in international summerschools, workshops and conferences. The host institution has assured me that such activities will be encouraged. Links with industry / industrial relevance (22)