POLARIZATION RESPONSE OF A DIELECTRIC CONTINUUM TO A MOTION OF CHARGE

In cases where dielectric relaxation dominates the time scale of molecular processes which involve the motion of charge (e.g., solvation dynamics, electron transfer reactions, or chemical reactions), the relevant time scale is the longitudinal relaxation time tau L, which is generally faster than the dielectric relaxation time tau(D). Numerical calculations of the polarizations P-D(t) with dE(t)/dt = 0 and P-E(t) with dD(t)/dt = 0 for an electrical RC network equivalent to an arbitrary dielectric function epsilon*(omega) are performed in order to generalize the relation between tau(L) and tau(D) which only for the Debye case reads tau(L) = tau(D) epsilon(infinity)/epsilon(s). The results for non-Debye systems as a function of relaxation time dispersion and relaxation strength are that [tau(L)] much less than [tau(D)]epsilon(infinity)/epsilon(s) whereas the decay profiles for P-D(t) and P-E(t) are similar. The normalized field decay P-E(t) represents a continuum model prediction for the Stokes shift correlation function C(t) observed in solvation dynamics experiments.