Surface Plasmon Resonance Enhanced Upconversion Luminescence Of Single Rare Earth Doped Nanocrystal By Single Gold Nanorod

Upconversion Luminescence?PL?is a process of producing higher energy photon emission at low energy excitation by light sources.Lanthanide-doped upconversion nanocrystals?UCNPs?have attracted the extensive attentions of researchers in biomedicine,nano optoelectronics,and information sciences due to their superior chemical and spectral properties relative to conventional organic dye molecules and semiconductor nanomaterials.And the upconversion spectrum can be tuned from visible light to near infrared region by changing the lattice hosts and doping ions of upconversion nanocrystals.However,the relatively low upconversion emission efficiency still limits their further development in practical applications.In order to enhance the upconversion luminescence of UCNPs for practical applications,we investigated the upconversion luminescence enhancement of single UCNP induced by single gold nanorods based on surface plasmon enhancement effect,and explored the optical properties and luminescence enhancement mechanism in this dissertation.In this dissertation,the enhancement effect of single gold nanorods on the upconversion luminescence of single NaYF₄:Yb³⁺/Er³⁺/Mn²⁺ UCNPs is studied.Gold nanorods with the similar longitudinal surface plasmon resonance wavelength but different diameters?27.3 and 46.7 nm?are used to couple with single upconversion nanocrystals by atomic force microscope probe manipulation,respectively.The experimental results show that greater upconversion luminescence enhancement up to 110-fold with larger diameter nanorods are achieved due to larger scattering cross-sections and near-field enhancement.The enhanced luminescence exhibits a strong dependence on the excitation laser polarization relative to the nanorod long axis.Time-resolved measurements on rise and decay processes of upconversion indicates that the lifetims are all decreased.The FDTD theoretical simulations unveil that both excitation and emission rates are improved by the plasmonic effect of gold nanorods,agreed well with the experimental results.