Competition effect in diffusion-controlled reactions between ions

The first correction to the total flux of charged particles into a sink including the mutual influence of the other sink for the system of two charged static sinks is obtained. It turns out that the correction is negative for a high intrinsic rate constant and positive otherwise. It is shown that for attractive reactants the diffusive interaction effect may be neglected even in the case of fully diffusion-controlled reactions for large enough values of the Onsager length. Moreover the monopole approximation formula is suggested to describe the diffusive interaction between closely located sinks