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

利用新合成的复合纳米结构银/二氧化钛核壳纳米颗粒,研究了金属银纳米颗粒对碲化镉纳米晶层荧光的增强情况.结果表明,这种新型复合金属纳米结构能极大地增强发光纳米晶层的荧光强度.银/二氧化钛核壳纳米颗粒是以水合肼、硝酸银和四异丙氧基钛为原材料,利用胶体化学法在水溶液中合成.透射电子显微镜图片表明这种新合成的银/二氧化钛纳米材料基本上呈球形,有较为明显的核壳结构,中间黑色的核是银纳米颗粒,外层颜色较浅部分是二氧化钛壳层.另外,包裹二氧化钛壳层后,银纳米颗粒的表面等离子吸收带从409 nm红移至430 nm,也证实了这种新型核壳纳米材料的形成.将此合成方法得到的银/二氧化钛纳米颗粒和碲化镉纳米晶用旋转涂覆方法进行直接组合后,得到了银纳米颗粒对碲化镉纳米晶荧光的明显增强,并对其增强的物理过程进行了讨论.这种能够增强荧光团发光的新型复合银纳米结构将在发光器件、荧光成像、生物探测等方面具有一定的应用价值.

Fluorescence Enhancement of CdTe Nanocystals Induced by Ag/TiO2 Core-shell Nanoparticles

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.