Interactions of Fluorophores with Iron Nanoparticles: Metal-Enhanced Fluorescence

Different density iron nanoparticulate substrates were fabricated by thermal vapor deposition in order to study the interactions of fluorophores with iron nanoparticles. We observed metal-enhanced fluorescence (MEF), when fluorophores were placed in close proximity, in the near-field, to the iron nanoparticle deposited substrates. There is often a strong net absorption effect caused by the localized enhanced electromagnetic field of the incident excitation field, when the luminophore is placed near the metal. Subsequently,the electromagnetic field distributions around different size Fe nanoparticles were simulated using FDTD, which revealed that the maximum electric field intensity is predicted to occur over the ∼400−550 nm wavelength range. In addition, the decay time of fluorophores was also reduced near the iron substrates, suggesting both an enhanced electric field and a plasmon-coupling component are the mechanisms for fluorescence enhancement, consistent with our laboratory’s current interpretation of MEF.