FRESH Lecture: The Quantum Design of Photosynthesis
- Prof. Rienk van Grondelle
- Thursday 20 April 2017
2333 CC Leiden
Professor Rienk van Grondelle is full professor of Biophysics at the VU University Amsterdam and Academy professor of the Royal Academy of Arts and Sciences (KNAW). Since 2015 he has also been appointed as visiting professor of the University of Princeton to teach on the primary processes of photosynthesis.
In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary processes of energy and charge transfer. Based on quantitative modeling we identify the exciton-vibrational coherences observed in 2D photon echo of the photosystem II reaction center (PSII-RC). We find that the vibrations resonant with the exciton splittings can modify the delocalization of the exciton states and produce additional states, thus promoting directed energy transfer and allowing a switch between the two charge separation pathways. We conclude that the coincidence of the frequencies of the most intense vibrations with the splittings within the manifold of exciton and charge-transfer states in the PSII-RC is not occurring by chance, but reflects a fundamental principle of how energy conversion in photosynthesis was optimized.