Pair relaxation

Detailed kinetic exploration of the relaxation of the initially formed radical ion pair would probably be of most utility in addressing the question of the degree of charge separation in exciplex or in radical ion pairs. Rentzepis and coworkers have recently found that in strongly interacting donor-acceptor pairs, for example, indene-chloranil, the initially formed ion pair relaxes within a few picoseconds to an equilibrated solvated complex (67). Time-resolved resonance Raman spectroscopy has also been used recently as a kinetic monitor for radical ion reactivity (68). 

Gelabert H, Gauduel Y. (1996) Short-time electron transfer processes in ionic aqueous solution Counterion and H/D isotope effects on electron-atom pairs relaxation.Chem 100 13993-14004. 

The Argand diagram of the 2.2 M solution of Et NCl shows three relaxation processes typical for aqueous electrolyte solutions (1) ion-pair relaxation (r l = tip), (2) low frequency relaxation (rj, as 8 ps) of water, (3) high frequency relaxation a 1 ps) of water, in contrast to that of the 2 M solution of Bu NBr where the relaxation process (2) splits up into two processes. Figure 7 shows the concentration dependence of the... 

Similarly to the occupied orbitals, the first term of the right-hand side sums the orbital relaxation effects after the ionizations, the second term sums the electron-pair removal effects after the ionizations, and the third term sums the electron-pair relaxation effects before the ionizations (Pickup and Goscinski 1973 Szabo and Ostlund 1996). The discrepancy is, therefore, attributed to the SCF-induced orbital relaxations after the ionizations and the differences in the electron correlations (second-order perturbation effects) in the presence or absence of electrons. 

We begin with the application of the formalism to H2. A two-electron system is special since the ion (e.g., H2) has no correlation. Thus the exact IP differs from the Koopmans value only because of orbital relaxation in the N — l)-particle system and correlation in the N-particle system. In the language of the previous section, there is no pair relaxation term (PRX) since the N — l particle system has but a single electron. Moreover, in second order, the pair removal term is just the negative of the second-order perturbation energy of the JV-particle system. 

TaUe 7.6 Orbital relaxation (ORX), pair relaxation (PRX), and pair removal (PRM) contributions (fai a.u.) to the correction to Koopman theorem IP s for N2... 

For example, when the Maxwell model, Fig. 1 -9, is subjected to a stress relaxation experiment as in Fig. 1 -4, the force on each spring-dashpot pair relaxes exponentially expressed in terms of the modulus analogy, we have the contribution of the /th pair to the modulus, G, t), given by... 

The analysis of the observed concentration dependence of relaxation times Tjp(c) of the ion-pair relaxation region, reveals two superimposed modes, a diffusional rotation mode of the ion-pair dipoles and a kinetic mode due to the re-establishment of the undisturbed equilibrium = Cd2+, M +)... 

BARTHEL - The existence of superimposed orientational and kinetic modes follows from the concentration dependences of dispersion amplitude, jp(o>c) - Ip(oo,c) and ion-pair relaxation time, jp(c). Models of the ion pair used in connexion with Eqs. (22) and (28) to calculate particle densities make assumptions on the shape and dipole moment of the ion-pair dipoles. For... 

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