Metal-enhanced fluorescence from thermally stable rhodium nanodeposits

摘要

Different density rhodium nanoparticulate substrates were fabricated by electron-beam physical vapor deposition in order to study the fluorescence of close-proximity fluorophores to the high thermally stable rhodium nanoparticles. We observed an apparently constant metal-enhanced fluorescence (MEF), when fluorophores were placed in close proximity to rhodium nanoparticles before and after autoclaving of the substrates. Fluorophores with different emission wavelength maxima and free-space quantum yields have also been studied and can undergo different enhancements, a 2.5-fold increase in far-field luminescence was observed from 15 nm Rh films for Tinopal, and up to a 10-fold enhancement was observed for fluorescein. Similarly, the near-field fluorescence enhancement values were estimated to be ～125 and 500 fold, respectively. Further, the electromagnetic field distributions around different size Rh nanoparticles were simulated using FDTD to understand the wavelength dependence of the e-field. Our findings show that the decay time of fluorophores was not reduced near to the rhodium substrates, suggesting only an enhanced electric field component is the mechanism for fluorescence enhancement.