Reflection of light from monomolecular layers on metal surfaces

Abstract

A theory is presented of the electronic spectra, at optical frequencies, of a monolayer of dye molecules a fixed distance from a metal surface. The coupling of the exciton polariton states of the dye layer to the plasmon surface polariton modes of the metal leads to a large enhancement in the absorption of the dyes as measured by attenuated total internal reflection. This technique uses a prism to couple out the polariton modes of the monolayer–metal system. Model calculations that explore the type of phenomena expected are described for a cyanine dye monolayer close to a plane surface of silver.