Metal-induced fluorescence lifetime enhancement of quinaldine chromophore on gold nanoparticle surface

Abstract

The phenomenon of nanoparticle-induced fluorescence lifetime enhancement of protonated 8-propoxyquinaldine thiol derivatives, covalently attached to the surface of gold (Au) nanoparticles, is reported. The observed lifetime enhancement occurs due to the parallel orientation of the protonated PQT with respect to the Au nanoparticle resulting in the coupling of the dipole moment of the protonated species with its dipole image formed on the surface of the nanoparticle giving rise to a net decrease of the dipole strength of the chromophore. Fluorescence anisotropy measurements support the above observation. The studies presented here provide insight towards modulating the excited state properties of a fluorophore for proposed applications in sensing, non-linear optics, photovoltaics, etc.