Gl Guillermo Beltramo

Second harmonic generation from silver single-crystal electrodes

The second-harmonic (SH) signal generated from Ag(110), Ag(111) and Ag(100) electrodes in aqueous solutions were measured over a wide range of potentials. From the experimental data both the isotropic and anisotropic amplitudes were calculated as a function of the potential. The contributions from the bulk were also analyzed. The isotropic response was compared to the values predicted by a theoretical model based on jellium and pseudopotentials.

Interference second harmonic anisotropy at single crystalline silver-electrodes

Using a new approach, the interference SHG anisotropy, it is possible to unambiguously evaluate the nonlinear susceptibility coefficients, which describe the isotropic and anisotropic response of a metal electrode. We report on a first application of this method to single crystalline silver electrodes in a 50 mM aqueous solution of NaClO 4 . The isotropic coefficient a shows the strongest dependence on the electrode potential. Theory predicts that the real part a r = Re(a) should have a minimum near the potential of zero charge. A normalized plot of a r vs. the surface charge density σ shows a good agreement between experiment and theory in the range -20 μC cm -2 < σ < 20 μC cm -2 .