  Effects of the adsorption-desorption process on the immittance response of an
electrolytic cell are theoretically investigated in the framework of the
diffusional Poisson-Nernst-Planck (PNP) continuum model, when the generation
and recombination of ions is taken into account. The analysis is carried out by
searching solutions for the drift-diffusion equation coupled to the Poisson's
equation relating the effective electric field to the net charge density. The
effect of different ion mobilities on the immittance, i.e., situations with
equal and different diffusion coefficients for positive and negative ions, are
considered. A general exact expression for the admittance in the context of the
linear approximation is obtained.
