Kinetics electron transfer, general aspects

For systems such as these, which consist of electron transfer quenching and back electron transfer, it is in general possible to determine the rates both of quenching and of the back reaction. In addition to these aspects of excited state chemistry, one can make another use of such systems. They can be used to synthesize other reactive molecules worthy of study in their own right. The quenching reaction produces new and likely reactive species. They are Ru(bpy)3+ and Ru(bpy)j in the respective cases just shown. One can have a prospective reagent for one of these ions in the solution and thereby develop a lengthy and informative series of kinetic data for the transient. 

The rate expressions 6.25-6.29 are all of the general form shown in Equation 6.30, where X is a reagent, here phenol. (Note that, in the electrochemical literature, the electron transfer reaction is sometimes written as A + e B, rather than O + e 4> R, and the reaction orders as a and cb rather than o and V we are using this aspect of the original notation.) Thus, the first task in the analysis of the kinetics of a reaction is to determine the values of... 

Because of the large dielectric constant of water, electron transfer reactions in this liquid are strongly coupled to solvent polarization modes. The equilibrium solvent effects are well accounted for within the celebrated Marcus theory of electron transfer reactions [19]. The dynamic effects of electron transfer reactions have been the subject of many interesting discussions in the scientific literature and revealed some nice aspects of chemical kinetics in general, as articulated below. Study of the dynamics of electron transfer uses the results obtained in SD. 

The electrochemistry of a polymer-modified electrode is determined by a combination of thermodynamics and the kinetics of charge-transfer and transport processes. Thermodynamic aspects are highlighted by cyclic voltammetry, while kinetic aspects are best studied by other methods. These methods will be introduced here, with the emphasis on how they are used to measure the rates of electron and ion transport in conducting polymer films. Charge transport in electroactive films in general has recently been reviewed elsewhere.9,11... 

The thermodynamics of insertion electrodes is discussed in detail in Chapter 7. In the present chapter attention is focused mainly on the general kinetic aspects of electrode reactions and on the techniques by which the transport of species within electrodes may be determined. The electrodes are treated in a general fashion as exhibiting mixed ionic and electronic transport, and attention is concentrated on the description of the coupled transport of these species. In this context it is useful to consider that an electronically conducting lead provides the electrons at the electrodes and compensates the charges of the ions transferred by the electrolyte. 

In this volume, the first chapter focuses upon some chemical reactions discussed in sufficient detail so that the excited reaction products can be definitely identified. In the second chapter, some of the general rules are considered that govern the development of the potential-energy surfaces associated with the intermediate collision complex. The third chapter deals with the theoretical and experimental aspects of nonreactive interchange of energy among kinetic, rotational, and vibrational channels, while the fourth and fifth chapters focus upon some aspects of electronic energy transfer primarily between electronic and vibrational modes. Two short specialized chapters follow which deal with some of the important excited-state reactions in atmospheric and laser studies. 

---