Your SlideShare is downloading. ×
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Excitation Energy Transfer In Photosynthetic Membranes
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Excitation Energy Transfer In Photosynthetic Membranes

560

Published on

Published in: Education, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
560
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
7
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide
  • Transcript

    • 1. Excitation Energy Transfer in Light Harvesting Complex II Jiahao Chen December 15, 2004 PHYS 598 NSM
    • 2. Plants as Transducers
      • Light energy  Chemical potential energy
      • The light harvesting process
        • threshold of photochemistry
      M. Kamen, Primary Processes in Photosynthesis , Academic Press: NY, 1963 . This study Light harvesting ~ 0.5 – 100 ps
    • 3. Light Harvesting Complex II
      • Most common photosynthetic protein in plants
      • Energy funneled to reaction center
      • Trimeric in vivo
      • Study monomer properties
      • Components: chlorophyll a (pink), chlorophyll b (grey), protein (cyan).
      LHC-II from spinach. PDB code 1RWT. Liu et. al. , Nature , 428 , 2004 , 287-292.
    • 4. Objectives
      • Quantum and Statistical Physics
        • How long does it take to harvest energy?
      • Chemical Biology
        • What is the efficiency of light harvesting?
    • 5. The Origin and Nature of Excitation
      • Light absorption
      • Photon  exciton
        • electronic excited state
      Ground state hole electron exciton Excited state occupied orbital empty orbital photon
    • 6. How Energy is Transferred
      • Coulomb interaction
        • Coherent/Resonant
        • Incoherent/Hopping
      • Two mechanisms
        • Dexter
        • Förster
      • Range
        • <5 Å
        • 5-12Å
      Different Spin Correlations! hole electron D onor A cceptor Dexter D onor A cceptor Förster
    • 7. F örster Theory
      • Approximations
        • Time-dependent first-order perturbation theory  Fermi’s Golden Rule
        • (Transition) Dipole-dipole interactions only
        • Optically accessible states only
      • Förster formula
    • 8. How to Quantify Efficiency
      • Mean passage time
        • Average time needed to traverse the entire protein
      • Quantum yield
        • Fraction of excitons that make it from start to end
        • Assume dissipation to be the only competing process
    • 9. Computational Procedure Atomic coordinates Distances between centers of mass: R ij Identity: chlorophyll a v. b Transition dipole strength, f Orientation: k factor Förster rate: k ij Quantum yield,  Mean passage time:  results PDB literature parameters
    • 10. Dipole-dipole couplings in LHC-II
    • 11. Energy transfer rates for LHC-II (II) Fastest route Energy ends up sloshing between this pair
    • 12. Results
      • Strongest dipole couplings lead to fastest transition rates
      • Light harvesting efficiency: 98.7%
        • Excitons have half-life of 50 transitions!
        • Excitons can travel long distances before decaying
      • Mean passage time: 13.52 ps
        • Average transition time: 0.97 ps
    • 13. Conclusions
      • Numerical evidence support model of antenna complexes funneling energy to a reaction center
        • Pair that excitation prefers to move in one direction
          • Chl b (650 nm)  Chl a (670 nm) transition
        • Pair that excitation prefers to end up at
      • Directional preference in exciton transfer rates
    • 14. Acknowledgements
      • TCBG
        • Klaus Schulten
        • Melih Şener
      • Martínez Group
        • Todd Martínez
        • Hanneli Huddock

    ×