Fluorescence lifetime of a molecule near a diffuse surface: Coupling to surface polaritons

Abstract

For surfaces in which the electron density does not drop abruptly from its bulk value to zero, the spectrum of surface polaritons includes, besides the usual plasmon branch, additional branches, referred to as higher multipoles. The complete spectrum of polaritons is given for a simple two-step model of a surface. The coupling of these modes to an excited fluorescent molecule located near the surface is discussed. The change in the width of the molecular transition, due to decay via the surface polariton channels, should reflect the structure in the density of surface polariton states.