The screening occurs in a diffuse layer extending from the electrode to the bulk solution (Fig. ). While this potential drop typically occurs within a distance of 1-2 nm, it extends to ˜150 nm for the highly dilute 1µM CuSO 4 solution. This is due to the screening length or Debye length, λ D , being inversely proportional to the square root of the concentration ( λ D ∼ 9.7 n √ C [nm] for aqueous solutions with =80 at room temperature, where n is the ion valence and C the concentration in units of mM). The disassembly of the double layer is associated with the diffusion of ions from the interface to the bulk through the diffuse layer over a time τ D = ), which is remarkably close to the contact time threshold for deposition found in Fig. .