The Fluorescence Of Organic Molecules In The Metal And Porous Aluminum Surface Enhancement Effect

Surface-enhanced fluorescence is a new field developed rapidly in recent years. Many work have been done and lots of achievements have been obtained in the theoretical and experimental studies. It has been found that the surface-enhanced fluorescence has potential applications in the fields of biomedical, biological and chemical detection and sensing due to its high sensitivity and other advantages. It has great significance to study surface-enhanced fluorescence phenomenon. It is believed that the surface-enhanced fluorescence will become a powerful tool in the research of surface science, ultra-sensitive biological detection in the near future.In the study of surface enhanced fluorescence, the selection of the substrate is very important. The rapid development of nano-materials has showed many unique physical and chemical properties such as confinement effect and surface effect. In this thesis, the surfaced enhanced fluorescence effects of organic molecules have been investigated by using metal nano-materials as a substrate, and theoretical analysis has been made. The enhancement effect is studied when organic molecules of Rhodamine 6G (Rh6G) and acridine orange (AO) were absorbed onto the substrates of the mechanically polished metal and porous aluminum surface under the laser excitation. There are mainly two parts included in the thesis. The first part studied the fluorescence enhancement effect of mechanically polished metal substrate surface to Rh6G. The second part deals with the fluorescence enhancement effect of anodic aluminum oxide (AAO) surface to Rh6G and AO.The first partThe fluorescence enhancement effect of mechanically polished metal substrate surface to Rh6G moleculesWe have studied the fluorescence enhancement and quenching phenomena of the mechanically polished metal surfaces to Rh6G molecule using laser spectroscopy. It was found that the surfaces of silver, copper and aluminum could enhance the fluorescent radiation of Rh6G, but silver and aluminum surfaces showed better enhancement effects than that of the copper. Increasing the distance between Rh6G and the metal substrate surface, the fluorescence of Rh6G still be enhanced by the silver surface, but the fluorescence quenching effect was observed at copper surface. Based on the theory of surface plasmon oscillation at nano-structured metal surface, enhanced local electromagnetic field, plasma coupling radiation, surface morphology, the nature of extinction, and space between the substrate surface and molecules, we have analyzed the influence of these factors on the fluorescence enhancement effect. The second partThe fluorescence enhancement effects of anodic aluminum oxide (AAO) to Rh6G and AO.In this part, we have studied the fluorescence enhancement phenomenon when Rh6G and AO organic fluorescent molecules were absorbed on the anodic aluminum oxide surface. The results showed that the anodic aluminum oxide surface could enhance the fluorescence radiation of AO and Rh6G, and enhancement effect related to the size of the array. It was found that the enhancement effect is better for the array surface with 7μm holes in deep, 40-50nm diameter than that of 10μm holes in deep and 60-70nm diameter of anodic aluminum oxide. Comparing the fluorescence spectra of AO and Rh6G molecules in aqueous solution with same concentration, we found that the photoluminescence spectra of organic molecules on the anodic aluminum oxide occurred a blue-shift in spectra.Analyzing its particular micro-porous surface structure of the anodic aluminum oxide surface, we found it has big adsorption capacity. The results showed that the anodic aluminum oxide is a better substrate for the fluorescence enhancement.