Surface-enhanced fluorescence of rhodamine 6G on the assembled silver nanostructures.

The fluorescence emission and enhancement of Rhodamine 6G on the silver island films (SiFs) with and without 4-Aminothiophenol molecules have been investigated. It was found that the SiFs without 4-Aminothiophenol molecules (PATP) have less contribution to the fluorescence enhancement. However, when PATP molecules as a spacer were deposited on the SiFs, obvious fluorescence enhanced effect was observed. The results show that the fluorescence enhancement depends on the morphology of the substrate surface and the distance between fluorophore molecules and the substrate surface. The experimental observations can be explained by local surface plasmon resonance and local field enhancement theory.

Surface enhanced fluorescence of physically polished nanostructured metal surface: the effect of the native oxide layer.

The fluorescence emission of Rhodamine 6G molecules at the physically polished nanostructured copper surface with varying thickness of the native oxide layer was investigated. The quenching effect was observed when the dye molecule was directly adsorbed onto the substrate surface without the formative oxide layer. However, the fluorescence was enhanced obviously when the native oxide layer was formed at the substrate surface. The experimental observations were discussed by taking into account the formation of the native oxide layer, the non-radiative energy transfer process and the local surface plasmon resonance at rough copper surface. The study highlights the importance of the native oxide layer formed on the metal substrate in surface enhanced fluorescence.

Fluorescence enhancement of modified silver nanoparticles.

Surface enhanced fluorescence (SEF) effect of acridine orange fluorophore in the proximity of silver nanoparticles (NPs) has been investigated experimentally in the aqueous solution system. It was found that the SEF effect could be influenced by the distribution of the NPs and the separation between the fluorophore molecule and metal surface. The fluorescence enhancement was improved significantly when Ag NPs was capped with 4-Aminothiophenol (PATP) that was acted as an isolating layer between the metal surface and fluorophore molecules. The results suggest that a proper distribution of metallic NPs and proper separation between fluorophore molecule and the particle surface are important for obtaining an optimal SEF effect.