On the dielectric decrement of electrolyte solutions: a dressed-ion theory analysis

Based on the dressed-ion theory and a simple physical argument regarding the conductivity of the solution, we derive a relation between the ionic strength and dielectric constant of an electrolyte solution. At its simplest, this model gives the dielectric constant at low ionic strength I as ε_r(I) = ε_r(0)(1 + αI)^-1, where α (the excess polarization) is directly related to the dressed-ion charge. One contribution to the origin of the dielectric decrement is thus seen to stem from the electrostatic screening of the ions in solution, with no solvent contributions necessary.