Photoinduced electron transfer in polar solutions. 2. New aspects of the role of the solvent mode in electron-transfer processes in charge-recombination reactions and comparison with charge-separation reactions
By using a new aspect of the polar solvent mode, that is, that its vibrational frequency is much smaller in the neutral state of the reactants than in the charged state, the authors formulated the charge-recombination rate. Numerical calculations show that in strongly polar solvents, the solvent mode apparently refuses to contribute to the Franck-Condon overlap. As a result, the charge-recombination rate is determined almost exclusively by the intramolecular quantum mode, which varies considerably from molecule to molecule, and by the magnitude of the electronic interaction between the electron donor and acceptor. The result that the solvent mode scarcely contributes to the Franck-Condon overlap in strongly polar solvent is in a marked contrast to that of the charge-separation reaction investigated previously. The condition for the high yield and high stability of the charge-separated state in a polar environment is investigated in detail. As a result, it has been found that the weak and strong dependences of the charge-separation and the charge-recombination rates, respectively, upon the energy gap, which have been demonstrated for the first time by introducing the new aspect of the solvent mode, can afford a favorable condition for an efficient photoinduced charge-separation process. 13 references, 8 figures.
- Research Organization:
- Nagoya Univ., Japan
- OSTI ID:
- 6240245
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 89:22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ELECTRON TRANSFER
CHEMICAL REACTION KINETICS
SOLVENT PROPERTIES
RECOMBINATION
PHOTOCHEMISTRY
ENERGY LEVELS
FRANCK-CONDON PRINCIPLE
MATHEMATICAL MODELS
THEORETICAL DATA
VIBRATIONAL STATES
CHEMISTRY
DATA
EXCITED STATES
INFORMATION
KINETICS
NUMERICAL DATA
REACTION KINETICS
400500* - Photochemistry