Energy transfer from an excited dye molecule to the surface plasmons of an adjacent metal

The probability for direct energy transfer from a dye molecule to the surface plasmons (SP) on a nearby metal is calculated using the classical Sommerfeld model. For 600-nm emission from a dipole-oriented ⊥ to an Ag surface, the peak SP coupling probability is 93% at a distance of 120 nm from the metal. The coupling is demonstrated in experiments with an Ag film between a rhodamine–methanol solution and a high-index prism. The SP-coupled radiation produces an intense cone of radiation in the prism, each frequency component of which satisfies the SP dispersion relation.