Clearing field recombination

By contrast, few such calculations have as yet been made for diffusional problems. Much more significantly, the experimental observables of rate coefficient or survival (recombination) probability can be measured very much less accurately than can energy levels. A detailed comparison of experimental observations and theoretical predictions must be restricted by the experimental accuracy attainable. This very limitation probably explains why no unambiguous experimental assignment of a many-body effect has yet been made in the field of reaction kinetics in solution, even over picosecond timescale. Necessarily, there are good reasons to anticipate their occurrence. At this stage, all that can be done is to estimate the importance of such effects and include them in an analysis of experimental results. Perhaps a comparison of theoretical calculations and Monte Carlo or molecular dynamics simulations would be the best that could be hoped for at this moment (rather like, though less satisfactory than, the current position in the development of statistical mechanical theories of liquids). Nevertheless, there remains a clear need for careful experiments, which may reveal such effects as discussed in the remainder of much of this volume. 

For Rd > L one gets R ff RD, while if Rd < L, R L. Accuracy of this formula when Rd L is not clear. To check it up, calculations were done for two typical cases corresponding to shallow donors in semiconductors (ro = 20 A) and deep centres in ionic reaction (ro = 2 A) [65], In the first case the reaction is controlled by a drift in the Coulomb field, when L > Rd within all the intervals of the diffusion coefficients considered (Fig. 4.5(a)) whereas in the second case, quite on the contrary, the recombination is controlled by tunnelling (Fig. 4.5(b)). What is surprising, that in both cases equation (4.2.31) describes the explicit result very well even if Rd L It could be shown that has to exceed the L by the value L/2... 

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