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The First Events Of Photosynthesis. The Design Of A BioSolar Cell Rienk van Grondelle.

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Presentation on theme: "The First Events Of Photosynthesis. The Design Of A BioSolar Cell Rienk van Grondelle."— Presentation transcript:

1 The First Events Of Photosynthesis. The Design Of A BioSolar Cell Rienk van Grondelle

2 Photosynthesis Stores About 8x The Total Worlds Energy Need

3 Waar vindt de fotosynthese plaats?

4 The Photosynthetic Membrane

5 Top-view of the Photosystem II-LHCII supercomplex

6 Peripheral Light-Harvesting Complex II of Plants. Binds 50% of all Chlorophyll on this planet

7 From Photosynthesis to Artificial Photosynthesis The major design principles of photosynthesis

8 1. Excitons The effective energy storage in antenna complexes is possible due to the presence of light-harvesting pigments (chlorophylls, carotenoids, bilins) with long-lived excited states and a high cross-section for light absorption. The elementary excitation of the antenna is described by the wavefuction n, which correspond to excitation of the n-th pigment. Quantum mechanics dictates that when neighbouring pigments are coupled because they are closeby, the excited state of the complex is given by a superposition of such wavefunctions, i.e. c1 n1 +c2 n2 +…, where one elementary excitation is shared between a number of molecules. Such a collective excitation (denoted exciton) is different from independently excited molecules n1, n2,… due to correlations (coherences) between them given by c1*c2…… Such coherences can be produced if the electronic Hamiltonian contains off-diagonal terms, i.e. H n2 n1. In this coherent state one molecule knows about the excitation of its neighbours. This dramatically changes the spectrum of a pigment aggregate as well as the energy transfer dynamics. In natural antenna complexes these features produce more efficient light absorption, faster conversion from short- to long-wavelength spectral bands, and increase the irreversible trapping of excitations by the RC.

9 Transfer rates between two Chl molecules (as a function of the energy gap and interaction energy between them) calculated according to modified Redfield (A) and Förster (B) expressions. The specific non-monotonous dependence of the rates on the energy gap and interaction energy is determined by the shape of exciton-phonon spectral density for Chl.

10 Relaxation in the Exciton Manifold of LH2 k-th exciton state Bottleneck Relaxation between one- exciton states (k,r) and (p,s), where k r and p s for coherence transfer or decay, or k=r and p=s for population transfer, is given by the term nm c nk c np c mr c ms J kp.

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12 Peripheral Light-Harvesting Complex II of Plants. Binds 50% of all Chlorophyll on this planet 4 nm

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14 Energy Transfer in PE545; a peripheral light- harvesting complex from cryptophyte algae

15 From Photosynthesis to Artificial Photosynthesis The major design principles of photosynthesis

16 2. Quantum Coherence

17 From Photosynthesis to Artificial Photosynthesis The major design principles of photosynthesis

18 3. High pigment/protein ratio: ultrafast (< 1 ps) energy transfer Plant PSI >30% of the mass is pigment!!!! Mg-Mg-distance about 1 nm Couplings of cm ps trapping time

19 From Photosynthesis to Artificial Photosynthesis The major design principles of photosynthesis

20 4. Long exciton lifetimes when the Reaction Center is absent or no concentration quenching. Antennalifetime LH1~1 ns LH2~1 ns CP47~4 ns LHC II~2 ns Chlorosome~200 ps Chl a aggregates< 20 ps Stark ??

21 From Photosynthesis to Artificial Photosynthesis The major design principles of photosynthesis

22 5. The Supra Molecular Organization 1950s 20 nm 2004

23 Architecture and constituents of a spherical chromatophore vesicle from R. sphaeroides constructed from AFM/LD data (37, 39) Şener M. K. et.al. PNAS 2007;104: ©2007 by National Academy of Sciences

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25 From Photosynthesis to Artificial Photosynthesis The major design principles of photosynthesis

26 6. Multiple Pathways for Energy Transfer and Many Entries into the Reaction Center Chls at 3-4 nm transfer excitations in ~10 ps!!!

27 The RC-LH gap: Förster vs. Marcus Chlorophylls at 3-4 nm transfer excitations into the RC in ~ 10 ps. * * e-e- e-e- And electrons out of the RC in ~1 second!!!!!!

28 From Photosynthesis to Artificial Photosynthesis The major design principles of photosynthesis

29 7. Multiple Pathways for Light- Driven Charge Separation

30 3 ps 1 ps Zinth cs. In The Bacterial RC Charge Separation Originates From The Special Pair

31 In RCs of green plants There is NO special pair

32 1

33 1 Experimental Evidence For Two Paths in the PS2 RC Romero et al,submitted

34 Pigments in The Active Branch of the RC Scherz et al, 2010

35 From Photosynthesis to Artificial Photosynthesis The major design principles of photosynthesis

36 8. Photoprotection in LHCII 3 Chl-> 3 Car Peterman et al, 1995

37 DCMU 1 min P AL Fo Fm NPQ To Regulate The Energy Flow The Light-Harvesting Antenna Has The Ability To Switch Off!!! Non-Photochemical Quenching Fluorescence Yield Time

38 Chl 1 Chl 2 Car T kQkQ kTkT kRkR Annihilation Chl 1 Chl 2 Q k1k1 γ γ kTkT K Lhc2 quenching: Target Analysis With a Real Annihilation Model Car*

39 Chl aLut1 Qy S1S1 NPQ a611 a612 a610 Neo Lut1 A B Is LHCII a Switch??????

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41 Principles Excitons\ Quantum Coherence Concentration Spatial Organization Supramolecular Organization Multiple entries to catalytic center Multiple ET pathways Photoprotection

42 Acknowledgements Vladimir Novoderezhkin, Alexander Doust, Jan Dekker, Chantal van der Weij-de Wit, Ivo van Stokkum, Bruno Robert, Alessandro Marin, Tjaart Krueger, Natalia Pawlowicz, Sandrine dHaene, Henny van Roon, Maxime Alexandre, Thomas Cohen Stuart, Cosimo Bonetti, Rudi Berera, John Kennis, Neil Hunter, Marcus Wendling, Eli Romero, Christian Ilioalia, Mariangela DiDonato, Manolis Papagiannakis, Mikas Vengris, Delmar Larson, Herbert van Amerongen, Marloes Groot, Miguel Palacios, Raoul Frese, Greg Scholes, Roberta Croce, Andy Stahl, Graham Fleming, Leonas Valkunas, Andy Pascal, Lavanya Premvardhan, Gert van der Zwan, Sacha Ruban, Peter Horton, Jos Thieme, etc etc


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