ELECTROCHEMICAL CONTORL OF SIGLE ELECTRON TRANSFER AT INTERFACES IN SOLUTION

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Ag nanoparticles(d = ca. 20 nm) adsorbed on the surface of a glass plate immersed in pure water dissolved when white light was irradiated under application of an external electric field. Dissolution was monitored via change in absorption spectrum. Structural characterization revealed that the number of Ag nanoparticles on the glass decreased as a consequence of the treatment. The size of the particles, however, increased to ca. 80 nm following the treatment. The rate of change in the structure was dependent on both the irradiated light intensity and the existence of an external electric field. The results demonstrate that photo-excitation combined with the electric polarization of Ag nanoparticles in solution leads to structural changes in Ag nanoparticles adsorbed on a glass plate. The changes were attributable to the highly localized electrochemical reactions of metal dissolution/deposition on the surface of the Ag nanoparticles.Metal nano-contacts of Cu, Ag, Ni, Pd and Pb were successfully fabricated via the electrochemical etching or deposition method at a gap of a sustainable thin gold wire in solution. Relatively stable behaviors of the conductance quantization exhibiting a unit value were apparent at the contacts of Cu, Ag, Ni, and Pd. Conductance quantization behavior of the Pb contact was rather unstable in comparison with other metals. The conductance quantization of Ni, Pd and Pb nano-contacts in solution at room temperature was observed for the first time in the present system.