Mixed-metal substrates for applications in metal-enhanced fluorescence

Over the last decade Metal-Enhanced Fluorescence (MEF) has emerged as the next generation of fluorescence spectroscopy, i.e. near-field fluorescence. However, in contrast to our collective knowledge and understanding of classical far-field fluorescence, we know relatively little. MEF is a consequence of the near-field interactions of fluorophores (dipoles) with the surface plasmons generated in plasmon supporting materials, where the optical properties of the metal afford for a wavelength dependence of MEF. In this paper we show that we are not limited to the properties of the individual metals for MEF, but in fact, surface deposits of mixed metals can create new dephased plasmon resonance bands, not present in the individual metals themselves. Subsequently, mixed metal substrates (MMS) offer significant opportunities for the multifarious and forever growing applications of MEF.