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Electron transfer in nonpolar media.
1Department of Physics and School of Molecular Sciences, Arizona State University, PO Box 871504, Tempe, AZ 85287-1504, USA. dmitrym@asu.edu.
Physical Chemistry Chemical Physics : PCCP
|January 15, 2020
Summary
Electron transfer in nonpolar solvents is driven by molecular translations, not dipole orientations. This leads to significant reorganization energy and non-Arrhenius kinetics, impacting electron transfer rates.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Theoretical Chemistry
Background:
- Marcus theory explains electron transfer via dipole fluctuations, suitable for solids.
- This model is inadequate for molecular liquids where density fluctuations dominate.
Purpose of the Study:
- To investigate electron transfer mechanisms in nonpolar solvents using perturbation liquid-state theory.
- To analyze the role of molecular translations and density fluctuations in electron transfer.
Main Methods:
- Application of perturbation liquid-state theory to model electron transfer.
- Analysis of reorganization energy dependence on solvent properties and solute size.
- Investigation of the fluctuation-dissipation theorem in the context of density fluctuations.
Main Results:
- Reorganization energy in nonpolar solvents is nonzero (0.1-0.3 eV), scaling quadratically with solvent polarizability and inversely with solute size.
- Density fluctuations, driven by molecular re-packing, violate the fluctuation-dissipation theorem for the energy gap variance.
- A hyperbolic temperature dependence of reorganization energy predicts non-Arrhenius kinetics for electron transfer.
Conclusions:
- Molecular translations, not dipole orientations, are key to electron transfer in nonpolar liquids.
- The study reveals significant reorganization energies and predicts novel temperature-dependent kinetics for electron transfer processes.
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