ON THE TIME-DEPENDENCE OF THE FORMATION OF CONDENSED URACIL FILMS AT THE MERCURY ELECTROLYTE INTERFACE

The formation of a condensed film of uracil at the mercury/electrolyte interface was investigated by measuring the instantaneous differential capacitance resulting from a potential step. The "short-time" transient can be described theoretically either by a two-dimensional progressive nucleation mechanism with a positive induction period or by two-step nucleation according to an exponential law and a constant growth rate. The dualism of the mechanism is independent of the uracil concentration, the temperature and the nature of the supporting electrolyte. The overall rate parameter bf decreases at constant ionic strength in the following sequence: F- ≈= NO-3= ClO-4 ≈ SO2-4 > Cl- > Br- > SCN- > I-. © 1990.