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Energy and Electron Transfer

Energy and Electron Transfer. MMP+ discussion Chapter 7 first half December 17, 2002 Zhiqiang Liu. Transfer. Competing Processes upon encountering. Trivial Mechanism for energy transfer. Spectral Overlap Integral. Trivial Mechanism for electron transfer.

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Energy and Electron Transfer

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  1. Energy and Electron Transfer MMP+ discussion Chapter 7 first half December 17, 2002 Zhiqiang Liu

  2. Transfer

  3. Competing Processes upon encountering

  4. Trivial Mechanism for energy transfer

  5. Spectral Overlap Integral

  6. Trivial Mechanism for electron transfer http://chemed.chem.purdue.edu/demos/main_pages/9.4.html

  7. Non-trivial energy transfer

  8. Forster Theory of Coulombic Energy Transfer dipole-dipole interaction 2: orientation. Alignment factor J: overlap. Energy match of donor and acceptor R: distance between dipoles

  9. Energy transfer by electron exchange Dexter:

  10. Comparison: Forster v. Dexter Forster: Dexter: • Dependence on separation. Dexter much stronger than Forster. • Forster depends on oscillator strength. • Both dependent on J. • Dexter involves excited states

  11. Generating D and A*

  12. Triplet Triplet Annihilation. Energy transfer via electron exchange

  13. Electron Transfer

  14. Excited states: better oxidizing and reducing agents

  15. Free energy for gas phase electron transfer

  16. Free energy in solution phase Gas phase results + terms for solution G Electrochemical potential in solution

  17. Coulombic term in free energy of electron transfer

  18. Libby vs. Marcus theory Frank-Condon e Jump • Three events: • Electron transfer • Molecular reorientation • Solvent reorientation Libby: Molecular and solvent after Electron. Marcus: Assumptions: 1. Loose bonding between molecules for classical phys/chem analysis 2. Geometrical and solvent reorientation to provide energy for the e jump

  19. Libby vs. Marcus theory

  20. Marcus for non zero free energy difference

  21. Experimental evidence for Marcus Inverted Region

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