【作者】 赵红艳；

【导师】 宋峰；

【作者基本信息】 南开大学 ， 光学， 2013， 博士

【摘要】 本文系统介绍了金属纳米颗粒的制备、表征以及应用,回顾了研究金属纳米颗粒局域表面等离子体共振特性常用的理论模型、理论方法和模拟软件做了简要的回顾。金属的材料特性、形状、尺寸等都是影响金属纳米颗粒光学特性的关键因素,纳米颗粒和荧光物质之间的距离也是影响荧光物质发光强度的主要参数。荧光物质的选择又分为有机物和无机物。本文在研究金属纳米颗粒局域表面等离子体共振(LSPR)特性的基础上,就金属纳米颗粒对中药有机成分蛇床子素的荧光淬灭现象,金属纳米颗粒对稀土离子铕离子的发光影响,从理论和实验两个方面做了系统的研究和分析。其主要内容如下：一：我们先用FDTD软件模拟了金属银纳米颗粒的LSPR特性,就颗粒的尺寸、形状、外界折射率等几个方面分析了影响银纳米颗粒局域表面等离子体共振特性变化的因素。同时指出,颗粒的形状对影响金属纳米颗粒LSPR共振峰位置的影响远大于其它几个因素。根据银纳米颗粒的LSPR特性,我们模拟了不同外界折射率条件下,半径为12nm的球形银纳米颗粒共振峰的变化,说明纳米颗粒作为LSPR探测器的探测潜力。研究了不同浓度下白芷水溶液的荧光光谱以及不同pH值下白芷荧光光谱的变化。在白芷稀溶液的浓度由0.075mg/ml变化为2.5mg/ml的范围内,荧光强度和浓度呈线性正比关系。通过不同pH值下白芷溶液荧光现象的分析,验证了香豆素类化合物是白芷的主要荧光成分。计算了荧光量子产率,为白芷以后的研究提供了一个定量分析数据。研究了在球形银纳米颗粒存在条件下,中药白芷的荧光淬灭现象,并对现象产生的原因给出了简单解释,就淬灭现象得出更大范围内荧光强度和浓度的线性关系。二：通过荧光光谱、吸收光谱以及时间积分荧光光谱实验,研究了在银纳米颗粒的尺寸由5nm增加到25nm的过程中,中药有机成分蛇床子素荧光淬灭程度的变化。随着银纳米颗粒尺寸的增加,荧光分子荧光淬灭程度逐渐减弱。从辐射和无辐射衰减速率的角度出发对此现象做出了合理解释,利用Gersten-Nitzan模型从理论上分析了纳米颗粒对荧光分子发光强度的改变,实验和理论一致性很好。研究表明：动态淬灭和静态淬灭都是造成荧光分子荧光淬灭的原因。三、研究了半径为12nm的球形银颗粒和半径为20nm的球形金颗粒对稀土复合物Eu(TTFA)3发光的影响。当入射光波长为350nm时,掺杂银纳米颗粒的铕离子在612nm处的发光强度可增加2.5倍。除了满足纳米颗粒局域场增强外,纳米颗粒局域表面等离子体共振光谱和荧光分子吸收光谱的重叠度也是激发场增强荧光物质发光的另一个重要因素。通过准静态近似理论模拟了在平面波照射下单个金属纳米颗粒周围的场分布情况。当入射光波长等于金属纳米颗粒局域表面等离子共振波长时,场增强因子可最大。更多还原

【Abstract】 In this work, we firstly introduced the preparation, characterization and application of the metal nanoparticles, and then made a brief review on the theoretical models, theoretical methods and simulation software to study metal nanoparticles localized surface plasmon resonance characteristics. Metallic material properties, shape, size, etc. are the key factors for affecting the optical properties of metal nanoparticles. The distance between the fluorescent substances and nanoparticles are also the main parameters to affect the fluorescence emission intensity of fluorescent substances. The selection of the fluorescent substance is divided into organic and inorganic. Based on the study of the localized surface plasmon resonance(LSPR) characteristics of the metal nanoparticles, we made a systematic theoretical and experimental study for the fluorescence quenching phenomenon of the Chinese organic ingredients osthole, and the luminescence of europium ion under the presence of the nanoparticles. The main contents are as follows:(1) We firstly simulated the LSPR characteristics of the silver metallic nanoparticles by FDTD software, and analysed the changes of the localized surface plasmon resonance of the silver nanoparticles from the particle size, shape, the external refractive index and other aspects. We also pointed out that the effect of particle shape on the metal nanoparticle LSPR peak position is much larger than several other factors. According to LSPR characteristics of the silver nanoparticles, we simulated the formants change of spherical silver nanoparticles with the radius of12nm under the different external refractive index, indicating the detect potential for the nanoparticles as LSPR detector.In this paper, fluorescence spectra of Angelica aqueous solution with different concentrations and different pH values were carefully studied. The fluorescence intensity of the Angelica dilute solutions were linearly proportional to concentration from0.075to2.5mg/ml. Through the analysis of fluorescence phenomena of Angelica solutions with different pH values, the main active ingredient coumarin compounds of Angelica are the main source of fluorescence. The value of the fluorescence quantum yield of Angelica aqueous solution provides a quantitative reference for future study of Angelica. Finally, the fluorescence quenching phenomenon of Angelica luminescent molecules were researched in the presence of the spherical silver nanoparticles. This provides a new idea for the traditional Chinese medicine as a fluorescent probe applied to biology study. The fluorescence spectrometric method is expected to analyze various traditional Chinese medicines, and it can be applied to many different biomedical applications and provide a new platform for the examination and development of raditional Chinese medicines.(2) By means of absorption and fluorescence spectroscopic experiments, as well as time-resolved fluorescence experiments, we investigated the luminescence properties of osthole in the presence of spherical silver nanoparticles (AgNPs) with sizes ranging from5to25nm. Quenching of the fluorescence of osthole has been found to increase with the decrease of the sizes of the silver nanoparticles. We make a reasonable explanation for this phenomenon from the perspective of the radiation and non-radiation decay rate. Using the Gersten-Nitzan model, the experimental and theoretical results were compared, and the results are in good unity. Both dynamic quenching and static quenching mechanisms exist between osthole molecules and silver nanoparticles.(3) We studied the influence of20nm spherical gold nanoparticles(AuNPs) and12nm spherical silver nanoparticles (AgNPs) on the luminescence of europium complex Eu(TTFA)3. The maximum enhancement factor of the complexes mixed with AgNPs is about2.5at the wavelength of612nm, while350nm is chosen as the incident light. Besides the enhancement of the localized field, the overlap between the absorption band of fluorescent molecules and the localized surface plasmon resonance spectra of nanoparticles is another important factor for excitation field enhancement. By means of the quasi-static approximation theory, we calculated the distribution of the electric field around a single spherical metallic nanopaticle illuminated by plane wave. The simulation results show that the field enhancement effect is more obvious when the incident light is close to the resonance of the metallic nanoparticle.更多还原