Second harmonic generation studies of silver metal liquidlike films

Silver metal liquidlike films (MELLFs) exhibit second harmonic generation signals (SHG) that are clearly different from those produced by smooth silver films or those given by electrochemically roughened silver surfaces. These differences are consistent with the interfacial colloidal model proposed for the MELLFs. The polarization and enhancement of the SHG signals are rationalized quantitatively in a model consisting of noninteracting silver particles. The results show that the particles are very nearly spherical. Trends in the results can be possibly explained by small eccentricities that vary slightly in the various MELLF preparations. We also find the volume fraction of the silver cores at the uppermost layer of the film to be 6-21%. The time dependence of the SHG revealed a curing process, on the time scale of several hours, that is attributed to diffusional rearrangements of the silver particles within the film.