INSTABILITY OF NONEQUILIBRIUM FLUCTUATION IN ELECTROCHEMICAL NUCLEATION .2. DETERMINATION OF THE CRITICAL CONDITION

In the foregoing paper, part I, the mechanism of the fluctuations whic h are necessarily induced by the breakdown of the electrostatic equili brium was examined. Consequently, it was found that nonspecific adsorp tion of ions onto electrode surface is essential to the progress of nu cleation. It was also deduced that the critical condition for the unst able growth corresponds to the flat potential distribution in the diff use layer within the electric double layer. Therefore, using the facts that at the stable region of the fluctuations, the electrode is kept in the electrostatic equilibrium and apparently behaves as an ideal po larized electrode, a method to determine the critical potential by the extrapolation from the stable region was theoretically developed. As a result, the critical potential equations corresponding to the hat di stribution of the potential in the diffuse layer were obtained for var ious experimental conditions. By applying these equations to actual sy stems, the adsorbed states of ions at the interface can be examined. T herefore, the critical potential for silver nucleation onto platinum e lectrode in AgNO3+NaNO3 solution were measured. Consequently, no inten se specific adsorption of ions was observed, and it was concluded that a pair of Ag+ ion and NO3- ion are simultaneously adsorbed by the ele ctrostatic interaction. (C) 1995 American Institute of Physics.