title: The plasmonic engineering of metal nanoparticles for enhanced fluorescence and Raman scattering.
abstract: We have investigated the effects of tuning the localized surface plasmon resonances (LSPRs) of silver nanoparticles on the fluorescence intensity, lifetime, and Raman signal from nearby fluorophores. The presence of a metallic structure can alter the optical properties of a molecule by increasing the excitation field, and by modifying radiative and nonradiative decay mechanisms. By careful choice of experimental parameters we have been able to decouple these effects. We observe a fourfold increase in fluorescence enhancement and an almost 30-fold increase in decay rate from arrays of Ag nanoparticles, when the LSPR is tuned to the emission wavelength of a locally situated fluorophore. This is consistent with a greatly increased efficiency for energy transfer from fluorophores to surface plasmons, resulting in a significant increase in quantum yield. Additionally, spatial mapping of the surface enhanced Raman scattering signal from a nanoparticle array reveals highly localized differences in the excitation field.
authors: Department of Physics, King's College London, Strand, London, UK. nicholas.cade@kcl.ac.uk
authors: N I
authors: NI
authors: Cade
authors: T
authors: T
authors: Ritman-Meer
authors: K
authors: K
authors: Kwaka
authors: D
authors: D
authors: Richards
mesh_terms: D053768:Metal Nanoparticles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D013059:Spectrum Analysis, Raman / Q000379:methods*; D020349:Surface Plasmon Resonance / Q000379:methods*