ESR, line broadening

Esr line broadening. When one of the couples if uncharged, the electrostatic work term is approximately zero. Structural differences between the two species are also likely to be small (X small). The effect of solvent is contained in Using Eqns. (5.23) and (5.25)-(5.27), a plot of log A .xch vs (Dop -ZJ " ) should be linear with negative slope. 

For the most part, the methods described allow direct observation of reactants, products, or intermediates by monitoring the change in some physical property, such as absorbance, electrical conductivity, NMR and so forth. In addition, there is a section on indirect methods and special cases to describe competition reactions and slow exchange reactions, that is, those reactions not amenable to study by NMR or ESR line broadening. 

From observations of ESR line broadening and spin-lattice relaxation time in the presence of O2, it was concluded that the H atoms are constrained to be about 10 A from adsorbed O2 molecules, and that they are therefore in microslits rather than on a reasonably flat surface (72). The reactivity with C2H4 or O2 indicated in Table IV is not contradictory to this, since it is observed only at higher temperatures (above —150°) where the H atoms can presumably leave their protective slits by surface diffusion. 

Grampp and Jaenicke [36] have carried out detailed studies of solvent effects on the kinetics of electron transfer for a variety of organic redox couples. The kinetic data were obtained by electron spin resonance (ESR) line-broadening experiments for very fast reactions with rates close to the diffusion-limited value. Some of the reactions were clearly diabatic, and others adiabatic on the basis of the solvent effect. 

Lorentzian, as in the 3-D case, but with an effective F. Fixed Spin-Induced ESR Line Broadening frequency for motional narrowing that is (Dwc) > instead of D. Since Wc ( = Dx) D (= D ), it again appears that the 1-D features of the motion result in a less efficient narrowing than with a 3-D motion. 

Long and Hendrickson have synthesized copper (II/1) complexes of the general type (2) with various three-carbon and four-carbon connecting chains Rj and R2. From temperature-dependent ESR line broadening, the rate constant for Cu(II)- -Cu(I) exchange varies from below 2.2 x 10 s ... 

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