SHG Studies on Halide Adsorption at Au(111) Electrodes

Second-order optical nonlinear spectroscopy such as Second Harmonic Generation (SHG) is inherently sensitive to interfacial regions. Using our recently developed method of Interference SHG Anisotropy (ISHGA), the anisotropy of the SHG field E(2ω, ϕ)∝ ∑ n=0 m k n cos[n (ϕ+ζn)] = A+B cos(ϕ+α)+... can be measured (i.e., the variation of the 2ω-field generated during the rotation of the sample around the surface normal). This field can be separated into its various sources, denoted as A, B,..., permitting us to achieve information on the geometric and electronic structure of the interface and their changes upon potential and adsorption.