Fluorescence Enhancement of CdTe Nanocystals Induced by Ag/TiO2 Core-shell Nanoparticles
银/二氧化钛核壳纳米颗粒对碲化镉纳米晶的荧光增强研究

Metal-enhanced fluorescence from CdTe nanocrystals placed in close proximity to novel synthesized Ag/TiO2 core/shell nanoparticles films is studied. The Ag/TiO2 core-shell nanoparticles are synthesized in the aqueous solutions by colloid chemistry method. Transmission electron microscopy images show that mostly Ag/TiO2 core/shell nanoparticles are clearly core/shell structure and ball-shaped. The deep black cores are Ag nanoparticles and the light-colored shell are titania. In addition, the UV-Vis absorption spectra of Ag nanoparticles have a surface Plasmon absorption at 409 nm arising from the particles. A similar surface plasmon absorption due to Ag nanoparticles is observed for the titania-coated Ag nanoparticles at a wavelength longer than for the Ag nanoparticles. This absorption shift is caused by a high refractive index of the titania shell and strongly suggests a complete coverage of Ag nanoparticles with titania. The as-prepared Ag/TiO2 core-shell nanoparticles are assembled with the CdTe nanocrystals and spin-coated on the quartz glass. Significantly enhanced fluorescence emissions are observed, implying that enhanced fluorescence from Ag/TiO2 core/shell nanoparticles films is mostly due to an electric field enhancement effect. The current work is available for the applications in light emitting device, fluorescence imaging, and biological detection.