Electronic coupling factor

Since the values of i/ depend on several factors noted above, in the absence of additional data such as the temperature dependence of the electron transfer rate constants for i-2 it is difficult to analyze the apparent difference between i/ for the charge separation reaction and that of the radical ion pair recombination reaction. However, the difference between these two values of u is not unreasonable given that the charge separation involves oxidation of an excited state of the donor, while radical ion pair recombination involves two ground state radicals. Small changes in the nuclear coordinates of the donor and acceptor for these two reactions should be sufficient to produce the observed difference in i/. The electronic coupling factor between ZnTPP and AQ should be different than that between ZnTPP " and AQ". 

V is the electronic coupling factor (the resonance integral), v is the velocity of nuclear motion, and Sj and Sf are the slopes of the initial and final terms in the Q,r region. If the exponent of the exponential function is small, then... 

Note that each /5a(s,Sa) is associated with an electronic coupling factor 5a(Sd, Sa) within the ensemble average. The/g° (s, Sa) and fl ° (s, Sd) specify the donor and acceptor densities of states (D.O.S.), as described in Ref. 63. The dependence upon disorder is assumed to introduce a static offset of the origin, as is usually assumed. These D.O.S. represent the emission (absorption) line shape of the donor (acceptor), calculated without disorder (hence the superscript hom ) and without dipole strength. Ns and Na are area normalization constants such that 1/Ns = Jq°° dE/g° (s) and 1/Na = Jo°° d a)j° (E). 

Binuclear metal complexes often exhibit unusually low ET rates (33, 46, 75). And, at comparable separation distances, the rates of ET in ruthenium-modified proteins are well below those of bridged organic donor-acceptor compounds (90, 118, 126). It is of interest to consider how much of this difference is due to electronic coupling factors. For example, in the complex Os(II)(dioxA)Co(III), A j,(Os to Co) is 7.2 x 10 s (33, 46). Similarly, Ru(BCO)Co has a rate of less than 3.6 x 10 s (4). The Na(Sp)Bi compounds of Closs and Miller having a similar-sized spacer and a smaller driving force have ET rates of approximately 1 x lO s (20,... 

Electronic coupling factor when donor and acceptor are in closest contact... 

Quantum mechanical arguments that we introduce in Sects. 2.5 and 4.2 and develop more fully in Sects. 7.2 and 10.4 concur that electrOTi transfer requires AE to be close to zero. They also provide a quantitative relationship the golden rule) between the constant kg and the off-diagonal Hamiltonian matrix element or electronic coupling factor H ) that mixes the diabatic reactant and product states ... 

Qjtp) on increase of cp, 0, and tp. The increase (decrease) of the transition probability due to rotation is a consequence of the increase (decrease) of the vibrational overlap when the overall shape of I3 moves in the space spaimed by the occupation numbers ni, H2 and n-i. Note that the electronic coupling factor cancel in the expression (9,6, 0) (ifthere is a single-promoting mode). Due... 

The normal coordinates qi and q2 for the symmetric stretching and bending vibrations are then linear combinations of the symmetry coordinates Si and S2 used above for calculating the electronic coupling factor gn and qj = C33S3 is the asymmetric stretching coordinate [70]... 

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