Mechanisms for electronic energy transfer between molecules and metal surfaces: A comparison of silver and nickel

The phosphorescence lifetime of pyrazine above a Ag (111) surface has been measured as a function of molecule–metal separation between 10 and 420 Å. The distance dependence of lifetime is in accord with the predictions of the classical point dipole theory over this range of distances. Using this classical model, the decay of electronically excited pyrazine is separated into contributions from radiative decay, resonant surface plasmon excitation, and lossy surface wave damping. The relative importance of these decay channels is calculated for silver and nickel in the near UV, and the dominant mechanism for energy transfer to these two metals in this distance regime is interpreted in terms of the electronic structure of the metal.