Effects of Dyes, Gold Nanocrystals, pH, and Metal Ions on Plasmonic and Molecular Resonance Coupling

摘要

The effects of various factors on the resonance coupling between elongated Au nanocrystalsnand organic dyes have been systematically investigated through the preparation of hybrid nanostructuresnbetween Au nanocrystals and the electrostatically adsorbed dye molecules. A nanocrystal sample is chosennfor each dye to match the longitudinal plasmon resonance wavelength with the absorption peak wavelengthnof the dye as close as possible so that the resonance coupling strength can be maximized. The resonancencoupling strength is found to approximately increase as the molecular volume-normalized absorptivity isnincreased. It is mainly determined by the plasmon resonance energy of the Au nanocrystals instead ofntheir shapes and sizes. Moreover, the resonance coupling can be reversibly controlled if the dye in thenhybrid nanostructures is pH-sensitive. The coupling can also be weakened in the presence of metal ions.nThese results will be highly useful for designing resonance coupling-based sensing devices and for plasmonenhancednspectroscopy.