Plasma vibrations are periodic oscillations of free electrons in conductors. As electromagnetic waves they are quantized and the corresponding quasiparticles are the so called plasmons. Surface plasmons propagate on an interface, e.g. between a metal (solid) and a dielectric (liquid or gaseous). They contain a transversal oscillation component, hence they can be excited by light under well-defined optical conditions. The characteristics of these surface plasmons are highly sensitive to modifications of these interfaces, e.g. by adsorption of atoms or molecules. We developed an experimental set up to measure with millisecond time resolution and use this technique for in situ electrochemical processes.