Electron Tunneling in Chemistry - Chemical Reactions Over Large Distances

Abstract

1. Introduction. 2. Tunneling Phenomena in Physics and Chemistry. Tunneling effects in nuclear physics. Tunneling phenomena in atomic physics. Electron tunneling in solid state physics. Tunnel phenomena in chemistry. 3. The Theory of the Elementary Act of Electron Tunneling Reactions in Condensed Media. General concepts. Adiabatic approximation adiabatic and diabatic potential surfaces and wave functions. Dependence of the exchange matrix element on the distance between the donor and the acceptor and on their mutual orientation. General formula for the probability tunneling harmonic approximation the Franck-Condon approximation. Classical degrees of freedom. Quantum degrees of freedom. Connection of the probability of tunneling with the macroscopic characteristics of the medium. Non-adiabatic effects in electron tunneling. Electron tunneling accompanied by the emission or absorption of light. Conclusion. 4. Macroscopic Kinetics of Electron Tunneling Reactions in Condensed Media. Peculiar features of the kinetics of electron tunneling reactions in condensed media. The kinetics of electron tunneling reactions for immobile reagents. The influence of the external electric field on the kinetics of electron tunneling reactions. The influence of reagent mobility on the kinetics of electron tunneling reactions. 5. Methodology of Studying Electron Tunneling Reactions. Physical and chemical properties of the systems used for studying electron tunneling reactions. 2. Methodology of analysing the kinetic data for electron tunneling reactions. 6. Tunneling Reactions of Trapped Electrons. The nature of trapped electrons. Recombination of e tr with hole centres. Low-temperature reactions of e tr with acceptor additives. Tunneling reactions of e tr near the temperature of matrix devitrification effect of translational mobility of reagents on the kinetics. Long-range tunneling in the course of photoannealing of e tr . 7. Electron Tunneling in Reactions of Particles Other Than e tr . Electron tunneling reactions between inorganic ion radicals and transition metal compounds. Tunneling reactions of organic ion radicals. Electron tunneling reactions between metal compounds. Electron tunneling from electron-excited particles to acceptors. Tunneling recombination of donor-acceptor pairs in crystals. Tunneling reactions on solid surfaces. Comparison of the model of direct electron tunneling with alternative models. Conclusion. 8. Electron Tunneling in Biological Systems. Electron tunneling in the reaction centres of photosynthesizing systems. Electron tunneling in reactions involving chlorophyll and its synthetic analogues. Electron tunneling between macromolecules attached to proteins. Conclusion. 9. Electron Tunneling in Artificial Organized Molecular Structures. Photoseparation of charges in organized molecular assemblies. Intramolecular electron transfer in bridge molecules. Conclusion. 10. Conclusion. References. Appendix.