title: Excitation volumetric effects (EVE) in metal-enhanced fluorescence.
abstract: Metal-Enhanced Fluorescence (MEF) effects from different density silver island films (SiFs) and the effects of far-field excitation irradiance on the observed enhancement of fluorescence were studied. It is shown that MEF non-linearly depends on silver nanoparticle (NP) size/density, reaching a maximum value for SiFs made at a deposition time (DT) of ∼5 minutes, i.e. just before SiFs become continuous. Numerical simulations of the silver-islands growing on glass revealed that the near-field magnitude depends non-linearly on size and interparticle distance exhibiting dramatic enhancement at ∼10 nm distance between the NPs. In addition, a remarkable effect of modulation in MEF efficiency by far-field excitation irradiance has been observed, which can be correlated well with numerical simulations that show an excitation power volume dependence. The near-field volume changes non-linearly with far-field power. This unique observation has profound implications in MEF, which has rapidly emerged as a powerful tool in the biosciences and ultimately allows for tunable fluorescence enhancement factors.
authors.affiliation: Institute of Fluorescence, University of Maryland Baltimore County, 701 East Pratt Street, Baltimore, MD 21202, USA.
authors.forename: A I
authors.initials: AI
authors.lastname: Dragan
authors.forename: C D
authors.initials: CD
authors.lastname: Geddes
mesh_terms: D053768:Metal Nanoparticles / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D012834:Silver / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D008670:Metals; D012834:Silver