title: How exciton-vibrational coherences control charge separation in the photosystem II reaction center.
abstract: 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.
authors: A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskie Gory, 119992, Moscow, Russia. novoder@belozersky.msu.ru.
authors: Vladimir I
authors: VI
authors: Novoderezhkin
authors: Department of Biophysics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors: Elisabet
authors: E
authors: Romero
authors: Department of Biophysics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors: Rienk
authors: R
authors: van Grondelle
mesh_terms: D004735:Energy Transfer; D007700:Kinetics; D008958:Models, Molecular; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D014732:Vibration
chemical_list: D045332:Photosystem II Protein Complex