Experiments on optical second-harmonic generation as a surface probe of electrodes

Optical second-harmonic generation (SHG) has been used as an in situ probe of potential-dependent processes occurring at the metal–electrolyte interface. Differential capacitance measurements of the charging behavior of smooth silver surfaces have been made and compared with the simultaneously monitored SHG. The results show a correlation between the electrostatics of the interface and the second-harmonic response when the electrode is polarized within the double-layer charging region. The nonlinear second-harmonic response during electrochemical film formation has been compared with the potential dependence of the linear optical properties of the surface at ω and 2ω. Optoacoustic detection methods have been employed in these studies.