Theory of the Fe/sup 2 +/--Fe/sup 3 +/ electron exchange in water
The rate constant for the Fe/sup 2 +/--Fe/sup 3 +/ electron exchange is formulated as k/sub 23/ = ..integral../sup infinity//sub 0/ g/sub 23/(r) k/sub 23/(r) 4..pi..r/sup 2/ dr, a form which also is used to analyze the data for the nuclear spin relaxation in Al/sup 3 +/ induced by collision with Ni/sup 2 +/. It is assumed that the equilibrium pair correlation function g/sub 23/(r) is the same function of ionic composition and temperature in the two cases and that in the spin relaxation process the local rate constant k/sub 23/(r) has the form that may be deduced from the Solomon--Bloembergen equations. In the case of the exchange reaction the theory of k/sub 23/(r) is developed with respect to the contributions from slow inner shell or outer shell reorganization (activation) dynamics. It is concluded that in the present case these complications are not important and that the controlling dynamics is the crossing from the reactant to the product diabatic Born-- Oppenheimer surface. Neither the exchange nor the spin relaxation data can be accounted for if the smallest metal--metal distance in collisions is that given by the closest approach of the envelopes of the M(H/sub 2/O)/sup n/+/sub 6/ complexes. However, allowing for overlap of the envelopes as one complex pokes into the interstices of the other reduces the distance of closest approach from 6.9 to 4.5 A. Then one can find Gurney type models for the ion--ion forces in solution such that the model calculations are in good agreement with the experimental exchange and relaxation rate constants and their dependence on temperature and ionic strength, as far as the limited data for the last allow.
- Research Organization:
- Department of Chemistry, State University of New York, Stony Brook, New York 11794
- OSTI ID:
- 5935608
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 76:3
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CHEMICAL REACTION KINETICS
CHARGE EXCHANGE
IRON IONS
WATER
CORRELATION FUNCTIONS
RELAXATION
SPIN
ANGULAR MOMENTUM
CHARGED PARTICLES
FUNCTIONS
HYDROGEN COMPOUNDS
IONS
KINETICS
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
REACTION KINETICS
400201* - Chemical & Physicochemical Properties