Modification of spontaneous emission lifetimes in the presence of corrugated metallic surfaces

We report the results of measurements of the spontaneous emission lifetime of a ${\mathrm{Eu}}^{3+}$ complex in the presence of a nearby metal surface. The excited-state lifetime of the ions are measured as a function of their separation from both planar and periodically corrugated metallic surfaces. Several corrugated silver surfaces were used, each having a different combination of pitch and amplitude. No significant difference is found between data obtained for ions situated above a planar silver surface and those above corrugated surfaces that have pitches greater than the emission wavelength. However, for surfaces with a pitch less than the emission wavelength, differences are seen, and are shown to increase with increasing corrugation amplitude. Possible explanations for the observed differences are given, including a discussion of the role of surface plasmon polariton modes on corrugated metallic surfaces.