Effect of photo-irradiation and external electric field on structural change of metal nanodots in solution

The effect of an external electric field on the structural changes of Ag films on glass substrates of various thickness was investigated. Films consisted of continuous Ag particles dissolved upon application of an external electric field in solution. Although thinner Ag films exhibiting discrete island structures did not dissolve as a result of electric polarization, dissolution proceeded when photo-irradiation on the order of mW/cm2 was applied in concert with an external electric field. Structural alteration of the films was attributed to the changes in both the size and number of Ag nanoparticles. The rate of change was dependent on illuminated light intensity. The findings demonstrate that photo-excitation combined with electric polarization of Ag nanoparticles in solution leads to structural changes of Ag nanoparticles adsorbed on a glass plate. Alterations were due to the highly localized electrochemical reactions of metal dissolution/deposition on the surface of the Ag nanoparticles.