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 τL, which is generally faster than the dielectric relaxation time τD. Numerical calculations of the polarizations PD(t) with dE(t)/dt = 0 and PE(t) with dD(t)/dt = 0 for an electrical RC network equivalent to an arbitrary dielectric function ε*(ω) are performed in order to generalize the relation between τL and τD which only for the Debye case reads τL = τDε∞/εs. The results for non-Debye systems as a function of relaxation time dispersion and relaxation strength are that 〈τL〉 ≪ 〈τD〉ε∞/εs whereas the decay profiles for PD(t) and PE(t) are similar. The normalized field decay PE(t) represents a continuum model prediction for the Stokes shift correlation function C(t) observed in solvation dynamics experiments.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry