Fluorescence at a surface

Fluorescence emitted by atoms near a metal surface is used to study the coupling of the surface plasmon field of a dielectric substrate with a molecular electron transition. Explicit expressions are derived for the atomic and molecular lifetimes. It is shown that the "classical" phase shift of a plane wave accompanying reflection from the surface is responsible for changes in the atomic lifetime. Moreover, it is demonstrated that the dipole direction of an atom can be established by exposing the system to polarized radiation. The contribution of the surface plasmons and the surface roughness to the radiative decay constant is determined for molecular transitions. A comparison between image theory and energy transfer theory showed that the first may be extremely inaccurate for the description of molecules far from the surface or for a highly conducting substrate.