Abstract
The resonance excitation of surface plasmons by a laser beam is highly sensitive to the dielectric properties of the media involved. In addition, the electromagnetic field is localized in the vicinity of a thin metal film which strongly enhances the observed physical effects as compared to measuring without surface plasmon resonance (SPR). In the traditional SPR sensing technique the variations of the refractive index of the sample medium induce changes in the angle of the resonance excitation, thus providing integrated information on the mass of the material present within the adsorption layer. This information is obtained by observing the SPR curve, namely by monitoring the minimum of the angular distribution of the reflected light. The influence of an electric potential applied to a gold film on the surface plasmon resonance phenomenon at the metal-liquid interface was studied. The oscillating shifts of the resonance angle and a gradual average drift were observed with a voltage cycling at different rates for various aqueous solutions as an adjacent medium. For the theoretical description, a model including redistribution of charges at the double layer near the interface and the oxidation of the gold film was developed. It was found that a change of the electronic density at voltages below the oxidation potential and, in addition, the oxidation of the gold surface above this threshold are the main mechanisms accounting for the observed experimental data.
Lioubimov, Vladimir (2002). The effect of the potential on the surface plasmon resonance at a metal-liquid interface. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -L57.