Figure 2

The evolution of the electric field from the electrode surface is presented for the TBA in salt solution, where the DNA density (a) σ = 10¹² cm⁻² and (b) σ = 10¹¹ cm⁻². Curves A, B, C, D, E, F and G respectively correspond to the electrode potential of +300 mV, +200 mV, +100 mV, 0 mV, −100 mV,−200 mV and −300 mV. The positive electrode potential is able to change the electric field inside the DNA layer from negative to positive and the change depends on the DNA density as well as the magnitude of the electrode potential. The 15-mer TBA occupies the domain between 15 to 16.6 nm, along the z-coordinate normal to the electrode surface, which is marked in the figure. Curves for the positive, neutral and negative electrode potentials are colored red, black and blue respectively.