有机分子在金属及多孔铝膜表面的荧光增强效应

【作者】 蔡晓燕；

【导师】 郑海荣；

【作者基本信息】 陕西师范大学 ， 光学， 2009， 硕士

【摘要】 表面增强荧光是近年来迅速发展的一个新的研究领域。研究者们无论在理论还是实验方面,都做了大量工作,并取得了很多成果。现在,表面增强荧光由于灵敏度高等优点,在生物医学、生物传感和化学检测及材料科学等领域具有广泛的应用前景。对金属表面增强荧光现象的深入研究具有十分重要的意义,随着探究的深入,表面增强荧光技术可望成为表面科学研究、超灵敏生物检测研究的有力工具。在表面增强荧光的研究中,衬底的选择至关重要。与体材料相比,近年来迅速发展的纳米材料表现出了独特的物理、化学性质(如量子尺寸效应,表面效应等),引起了研究者的高度关注。本论文的研究中,我们用金属纳米材料作为衬底,研究了它们对有机分子光谱的影响,并进行了理论分析。主要研究了吸附在机械抛光金属衬底和多孔铝膜表面的有机分子罗丹明6G(Rh6G)和吖啶橙(AO)在激光激发下所表现出的荧光增强效应。论文主要分为两个部分:第一部分研究了机械抛光金属衬底表面对Rh6G的荧光增强效应:第二部分研究了多孔铝膜(AA0)表面对Rh6G和AO的荧光增强效应。第一部分机械抛光金属衬底表面对Rh6G的荧光增强效应利用激光光谱法对吸附在机械抛光金属表面的Rh6G分子的荧光增强和淬灭现象进行了研究探讨。发现金属银、铜和铝表面均对Rh6G的荧光辐射具有增强作用,而且银和铝表面的增强效果优于铜表面。当Rh6G荧光分子与金属衬底表面的距离增大到一定程度时,银表面仍会增强Rh6G的荧光辐射,而铜表面则表现出荧光淬灭效应。根据表面等离子体振荡导致局域电磁场增强和等离子体耦合辐射、表面形貌、消光性质、荧光分子与衬底表面之间的间距等因素,分析了纳米金属性质和构型对荧光增强效应的影响。第二部分多孔铝膜(AA0)对Rh6G和AO的荧光增强效应。对吸附在多孔铝膜表面的Rh6G和A0有机荧光分子的荧光增强现象进行了分析研究。结果表明多孔铝膜表面对Rh6G和A0的荧光辐射具有增强作用;并且增强效果与孔径大小有关,孔深为7μm,孔径40-50 nm的全透多孔铝膜增强效果最好。与同浓度的Rh6G和A0分子水溶液荧光谱相比,多孔铝膜上的有机分子的光致发光谱发生了蓝移,且表现出了更好的对称性。分析了多孔铝膜表面特殊的微孔结构所表现出的强的吸附能力。发现有机分子的荧光光谱线型的改变与有机染料分子周围环境的改变有关。更多还原

【Abstract】 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.更多还原