Electron Transfer Reactions In Solution Research Articles

On alternative activation mechanisms in electron-transfer reactions in solution

The model for electron-transfer kinetics in solution is considered. In one model the appropriate energetic condition for charge transfer is met by a small number of vibration-rotation states in thermal equilibrium with the solution. Collisional activation (CA) between ion in the solution and the solvent is the origin of such states. In another model CA is neglected and the appropriate energy states are regarded as being reached by the fluctuations in the energy of the ion, as a result of its interaction with many surrounding solvent molecules; this is the energy fluctuation (EF) model. The dependence of the charge-transfer rate upon the interfacial potential difference for the two models is outlined, and the differences between the models is discussed. Comparison with spectroscopic data for H3O+ in solution suggests that the energy distribution in the vibration-rotation levels in this ion is continuous and the classical modes of vibration exist in water. A supposed discontinuity, which would have annulled...

Theory of simple electron transfer reactions in solution

This paper reports the analysis of an electron transfer, oxidation-reduction reaction system. The model electron transfer system consists of a dielectric continuum solvent in which charged electron donor and acceptor reactants are dissolved. The reactants in this model behave as hard sphere entities with internal degrees of vibronic freedom; however, the hard sphere character is important only in connexion with the dynamics of the reactant's encounter during the course of the electron transfer. This model, therefore, apart from the internal vibronic degrees of freedom, is the same as that examined by Levich and Dogonadze. Our analysis of the model system employs the Yamamoto reaction rate theory to obtain electron transfer rate constant expressions. These derived theoretical rate constants are general; they apply to all reactions from those classified as chemically adiabatic to the non-adiabatic cases. The effects of internal vibronic degrees of freedom appear in the rate constant expressions both as additional terms in the energy exponent and in the pre-exponential factor. This manifestation of vibronic contributions is expressed in the pre-exponential factor as a power series in the temperature. The introduction of this additional dynamical dependence on internal degrees of freedom prepares the way to the theoretical consideration of more complicated electron transfer systems.

Generalized Mobility Theory of Electron Transfer Reactions in Solution

This paper reports a generalized theory of electron transfer reactions in solution; such reactions are typically termed oxidation-reduction reactions. The theory involves the use of the Kubo linear response analysis to examine the transport processes in an electrolyte system. In particular, we examine a system in which electron transfer between ions in the solution is possible. The substance of the theory is contained in an expression for the electron transfer rate constant. This rate constant is general, valid for all degrees of coupling between the electrons, ions, and surrounding dielectric medium. An expression of this type has not been reported previously. In deriving this general rate constant we find that there are new, hitherto unexpected processes which contribute to the electron transfer rate. Such processes are evident when, through the use of the Kubo theory, we examine the probability of electron transfer correlated with a simultaneous ionic diffusion step and a polarization displacement in the dielectric continuum. The degree to which these various transport processes contribute to the electron transfer rate is examined by means of a calculation on a model system. The system consists of two ionic species, one an electron donor and the other an acceptor, immersed in a dielectric continuum. The transfer electron is considered harmonically bound to the donor ion. The analysis is carried out without recourse to the Born-Oppenheimer separation approximation. We ignore the interaction between the transfer electron and the surrounding ions, but include a brief discussion of ways of handling this problem in the Appendix. This analysis of a model system points the way to future more detailed analyses of the problem.

A solvable model of energy transfer between electronic states which interact with a Boson field

A model of two electronic states linearly coupled to each other and to an arbitrary Boson field is proposed. The eigenstates and eigenvalues are evaluated exactly. Applications are suggested to sensitized luminescence in solids and electron transfer reactions in solution.

The mechanisms of some electron-transfer reactions in solution

Some recent studies of inner-sphere and outer-sphere electron-transfer reactions in solution are described. Various indirect criteria for determining the mechanisms of electron-transfer reactions and the question of ligand bridging at electrodes are discussed.

The theory of thermal electron-transfer reactions in solution

The theory of thermal electron-transfer reactions in solution

Free Energy of Nonequilibrium Polarization Systems. II. Homogeneous and Electrode Systems

The polar contribution to the free energy is calculated for a system containing ``particles'' imbedded in a continuum having nonequilibrium dielectric polarization. Each particle may either be a single molecule or a whole collection of molecules (such as an electrode) at specified nuclear configuration and may possess a general permanent and induced charge distribution. Thereby, the results of Part I of this series are extended to a variety of systems. It is also shown that the polar contribution to the free energy can be written as the sum of free energies of equilibrium polarization systems, thereby permitting the immediate application of literature expressions for the latter to calculating the former. This expression is also derived for systems possessing partial dielectric unsaturation under a certain typical condition. Applications are made to the theory of electron-transfer reactions in solution and at electrodes and to the theory of the shift of electronic spectra of polar solutes by polar solvents.

Adiabatic theory of outer sphere electron-transfer reactions in solution

Adiabatic theory of outer sphere electron-transfer reactions in solution