Reexamination of electrodiffusion time scales

The characteristic time scales in ac ionic conduction near equilibrium are reassessed via consideration of a selection of one-dimensional model problems. It is observed that, in addition to the two basic electrodiffusion time scales, those of diffusion relaxation in the macroscopic- and Debye-scale domains, T and tD (the latter identical with the bulk charge relaxation time), some intermediate time scales are present in each system. It is concluded that, due to insensitivity of the electric double layers to harmonic voltage disturbances, the short-time response on the tD scale is determined by the quasielectroneutral bulk.