Abstract
In this dissertation, we utilized the“surface plasmon resonance”effect of silver nanoparticles to study the metal-enhanced fluorescence effect for the fluorphore, YAG. We have demonstrated that polyvinylpyrrolidone (PVP), polyaniline (Pani) or it derivative ─ Pan-SBu, Pan-Cys can form a uniform coating layer on the surface of YAG particles, which can be used as the absorption layer for the silver nanoparticles on YAG, and meanwhile served as a spacer between silver nanoparticles and YAG particles. Auger electron nanosc ope (Nano-Auger) was used to analyze the elemental compositions for the particle surface, which is coupled with a high resolution SEM to help locate specific interested small area; the thickness of the polymer encapsulation and the distribution of silver nanoparticles on YAG surface were observed by high resolution transmission electron microscope (HR-TEM). The photoluminescence (PL) results showed that fluorescence emission intensity of YAG varied with the interval distance between YAG surface and the silver nanoparticles and is also very sensitive to the amount of the surface silver nanoparticles. Our results also indicated that Pan-SBu and Pan-Cys display stronger attractive force between the –SBu or –Cys functional group and silver. Most interestingly, the redox ability of the Pani chain can help reduce silver ion and grow silver nanoparticles directly on the YAG surface, which can greatly increase the use efficiency of silver nanoparticles. Furthermore, the amount of silver nanoparticles on the YAG surface should be appropriately controlled to prevent fluorescence quench by overdosed silver nanoparticles. We found that the optimal encapsulation thickness of Pan-Cys is about 10~15 nm, which lead to 1.25~1.50 fold enhancement on fluorescence intensity.