Analysis of Electromodulated Optical Second-Harmonic Response at a Metal/Electrolyte Interface Using a Local Surface-Site Charge-Displacement Model

Abstract

We present aspects of a general approach for the analysis of second-harmonic response at a metal/electrolyte interface. Analysis is based on a combination of principles from classical system identification and pattern recognition with a previously derived explicit and general representation of modulated second-harmonic response on the molecular level. This study emphasizes the adaptation of our approach and associated representation for the formulation of feature variables whose purpose is to extract features associated with observed trends in modulated second-harmonic signals. Our development introduces the concept of representing the multidimensional processes responsible for second-harmonic generation by means of a one-dimensional stationary stochastic process. This approach allows us to extract trends in experimental data correlated with molecular level charge displacements and resonant effects. The paper concludes with a series of analyses that illustrate the applicability of our approach and suggest possible pathways for its extension.