Spinless theory spin conversion

The irreversible quenching of the triplet Ruthenium complex by methylviologen [148] represented by Eq. (3.329) was considered within the spinless theory in Section VII. The more detailed reaction scheme accounting for the spin states and their incoherent conversion is as follows ... 

Only the result for the fast conversion (x —> oo) is identical to the spinless theory equation (3.208), provided k%/4 is substituted for kc in Eq. (3.205). Such a substitution conditioned by a full equilibration of the spin state populations results in a proper redefinition of the EM parameter z in highly polar solvents (C = 0) ... 

With the constraint (3.601) at any spin conversion (p(r) is exactly the same as in the equation of the spinless theory, (3.211). This is because the transitions between the singlet and triplet RIPs do not modulate their recombination rates, leaving z = kc/4na as well as product yields, 1 [Pg.318]

However, the theory of exciplex dissociation cannot be made spinless like that for photoacids (Section V.D). The dissociation products are radical ions and the spin conversion in RIPs essentially affects

other quantities listed in Eq. (3.589). To illustrate this phenomenon, let us concentrate on the fluorescence yield, which is affected through %E(ks) and the charge separation quantum yield cp(cr). We will consider the general solution obtained for these two quantities in Ref. 31 only in the simplest case of highly polar solvents for which the Green functions are well known. 

It is instructive to note that neither of these quantities depends on x if k r = kt. In this particular case the spin conversion does not modulate the rate of recombination so that cp = (1 + ksr/kD) l as in the spinless theory and w j is the weight of the singlet in the uncorrelated pairs composed in the bulk. 

The shape of the kernels (3.651) is rather obvious from the physical point of view. The kernels R and R are exactly the same as in Eq. (3.369) of the spinless theory. When spin conversion during encounter is negligible, the backward electron transfer to the ground state remains the single channel of geminate ion recombination. Therefore, the kernel R is 4 times smaller than... 

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