Resonant Interaction of Surface Plasmons with a Dye Monolayer

Abstract

Abstract Surface plasmons on silver films covered with organic monolayers (dye molecules (S 120) deposited on cadmium arachidate Scheibe or ϳ aggregate) are studied in detail. The optical properties of this system derived from reflection measurements can be described by a rather simple one electron oscillator model. The damping of its eigenfrequency is rather small due to the regular arrangement of the dye molecules. ATR measurements showed a strong influence of this narrow resonance on the dispersion relation of surface plasmons. These observations can be well described by the dielectric function derived from the reflection measurements. The dye molecules are deposited on a cadmium arachidate film of 27 Å thickness. In the case of more than one cadmium arachidate space layer between dye and metal the agreement of observed data with those calculated using the oscillator constants gets worse. This is explained by the decreasing order of the dye molecules in the ^'-aggregates with increasing number of space layers