Nemstian stationary conditions

Two groups of methods can be applied to this task equilibrium, which have already been considered above, and non-equilibrium ones. The latter, in turn, can be divided into stationary and nonstationary methods. The non-equilibrium methods can be applied only to Nemstian systems, which means that the electrode equilibrium is attained. Of course, the intervalence equilibria have also to be established. The whole system, however, is non-equilibrium because of the presence of diffusion fluxes of E(/) and B(/). These fluxes are constant at stationary conditions ... 

The general theoretical treatment of ion-selective membranes assumes a homogeneous membrane phase and thermodynamic equilibrium at the phase boundaries. Obvious deviations from a Nemstian behavior are explained by an additional diffusion potential inside the membrane. However, allowing stationary state conditions in which the thermodynamic equilibrium is not established some hitherto difficult to explain facts (e.g., super-Nemstian slope, dependence of the selectivity of ion-transport upon the availability of co-ions, etc.) can be understood more easily. 

Stationary values of the potential are measured, the concentrations at the electrode surface and in the bulk being not equal, and stationary diffusion fluxes of electroactive species being available in the system. Since the species at the surface are in equilibrium and the Nemst equation is still valid, we can denote such conditions as Nemstian. 

---