| The intent of this dissertation is theoretically and experimentally to elucidate the structure of the diffuse part of the electrical double layer at small currents.;We conclude that there is significant deviation from electroneutrality in the diffusion layer measured by Ibl and Muller as well as in the diffuse part of the electrical double layer at small currents. In other words, for small currents the distinction, which has been used to date, between the diffuse part of the electrical double layer (ion redistribution layer) and diffusion layer (local electroneutrality) must be corrected. Phenomenologically, we conclude that the diffusion layer is in fact the diffuse part of the electrical double layer at small currents. The charge distribution is the modified Boltzmann distribution, exp {-(z-c)qV*/kT}, as we have expected, where c is a parameter based on the Frumkin correction, self atmosphere effects, and the fluctuation potential model.;From the photovoltaic effect at the intrinsic Ge - electrolyte interface, we observed that the surface states are located at the intrinsic Ge surface due to oxide layers or adsorbed impurities which act as donors. From the relation of pH-potential variation at the intrinsic Ge-pH solution interface, we may assume that the potential drop in the diffuse part of the electrical double layer at small currents is close to the zeta potential ((TURN)25mV/pH).;A new experimental method has been developed to trace out the electrical potential profile which is significantly different from and complementary to Ibl and Muller's interferometric method for measuring the concentration profile in the diffusion layer. A Langmuir probe is moved over small distances with a piezoelectric crystal to measure the potential in the diffuse part of the electrical double layer. For zero electrical current through the double layer, the redistribution of ions is confined to a region from 10 to 10('3)(ANGSTROM) which is too close to the surface to be probed experimentally. When a small current is drawn through the double layer, the width of the double layer dramatically increases and extends out from 10('3) to 10('5)(ANGSTROM). This overlaps the diffusion layer 10('4) to 10('7)(ANGSTROM) as measured by Ibl and Muller. |
