Onsager radius geminate recombination

The course of the recombination processes in a particular system depends on several factors. One of the most important ones is the polarity of the system. Both geminate and bulk recombination processes are strongly influenced by the Coulomb attraction between electrons and cations, and the range of this interaction in condensed matter is determined by the dielectric constant e. The range of the Coulomb interaction in a particular system is usually represented by the Onsager radius, r, which is defined as the distance at which the electrostatic energy of a pair of elementary charges falls down to the thermal level kj,T. 

Interestingly, it has been shown that the recombination of the hydrated electron is greatly dominated by reaction with OH radical, because the reaction with HjO is not diffusion controlled despite the Coulombic attraction. Geminate ion recombination is usually considered to be negligible in water because the Onsager radius is small (0.7 nm) compared to the radius ofthe distribution of e, in the spur ( 2.3 nm) (Chapter 1). 

The most optimal conditions for monitoring quantum beats are in non-polar solvents for the following reasons [7] (1) the separation of the radial pair is usually much less than the Onsager radius and the radical ion pairs recombine geminately (2) a strong luminescence signal can be observed due to the small solvation energy ... 

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