Plasmon-modulated photoluminescence of individual gold nanostructures.

In this work, we performed a systematic study on the photoluminescence and scattering spectra of individual gold nanostructures that were lithographically defined. We identify the role of plasmons in photoluminescence as modulating the energy transfer between excited electrons and emitted photons. By comparing photoluminescence spectra with scattering spectra, we observed that the photoluminescence of individual gold nanostructures showed the same dependencies on shape, size, and plasmon coupling as the particle plasmon resonances. Our results provide conclusive evidence that the photoluminescence in gold nanostructures indeed occurs via radiative damping of plasmon resonances driven by excited electrons in the metal itself. Moreover, we provide new insight on the underlying mechanism based on our analysis of a reproducible blue shift of the photoluminescence peak (relative to the scattering peak) and observation of an incomplete depolarization of the photoluminescence.