Surface Plasmon-Mediated Decay Processes of Ions in Solids

This chapter focuses on how the emission characteristics of luminescent systems are affected by the presence of a smooth metallic layer. First, we examine the case of a metallic layer nearby to the most fundamental luminescent system — an isolated atom/ion or molecule. Because the metallic layer will adjust the photonic modes in the region near the layer, the radiative decay rate of a nearby excited atom will be altered. Additionally, the presence of the metallic layer allows the atom to interact with the plasmon field of the layer, which will in principle provide additional modes into which the atom could decay. It is this latter affect that is discussed in the first part of this chapter where we show that a modest increase in the radiative decay rate, and hence a corresponding increase in the Purcell factor, can be obtained. The dependence of the Purcell factor on the emission wavelength and on the atom-layer separation are explored. We next discuss another important luminescence-related process — ion-ion energy transfer — in the case when the ion pair is proximate to a smooth metallic surface. When the mirror is present, the energy transfer process may be mediated by surface plasmons, in addition to the traditional energy transfer process, which is mediated by virtual photons, at least in a quantum electrodynamic (QED) formulation of the problem. We find that though the plasmon-mediated energy transfer rate is much less than the traditional energy transfer rate for closely spaced ions, the plasmon mediated transfer rate could be the dominant process for certain experimental conditions.