【作者】 司民真；

【导师】 张治国；

【作者基本信息】 哈尔滨工业大学 ， 光学， 2010， 博士

【摘要】 表面增强Raman散射(SERS)具有灵敏度高、水干扰小及适合于研究界面效应等特点，广泛应用于表面配合物研究、吸附界面表面状态研究、生物大小分子的界面取向及构型构象研究、痕量有机物及药物分析、光化学反应的中间产物及终产物的结构分析等。在SERS研究中，SERS基底的制备一直是SERS技术最重要的研究领域,如何制备出高稳定性、高重复性、高普适性、高活性，且制备方法简单廉价的基底一直是人们追求的目标。本文以新型纳米银胶、纳米银膜的研制为主，并对其性质进行了系统地研究。利用量子力学从头算的原理，使用Gaussian’98软件包，计算了几种探针分子的Raman光谱，包括计算了氯霉素、甲基橙、甘氨酸、甘氨酸酐的Raman光谱。借助计算的Raman光谱对所获得的SERS谱进行指认，以获取探针分子在纳米银上的吸附方式和存在形式等信息。制备了正、负电性纳米银，对其性质进行研究。用柠檬酸三钠为还原剂制备出了外观为淡黄色的纳米银溶胶，电泳实验表明纳米银表面带正电。吸收谱及电镜照片显示正电性银溶胶吸收峰为398nm，平均粒径5nm。用单宁还原硝酸银制备出了外观为红棕色的银溶胶，电泳实验表明该纳米银表面带负电，吸收谱及电镜照片显示银溶胶吸收峰为418nm，平均粒径10nm。用阴离子型分子、阳离子型分子、中性分子和双离子型分子作为探针分子，进行SERS谱的测量，结果显示，正电性胶态纳米银适合作为阴离子型分子的基底，负电性纳米银适合作为阳离子型分子的基底；用室温下保存两年的负电性纳米银与新制备的负电性纳米银进行吸收谱、电镜、SERS谱的比较研究，得出负电性纳米银具有较好的稳定性，可重复性；对前后两次按同一方法制备的正电性纳米银进行电镜、SERS谱的测量，得出正电性纳米银具有较好的可重复性。以正电性纳米银及传统方法制备的纳米银为基底，进行阴阳离子型探针分子的SERS比较研究，表明正电性纳米银比常规方法制备纳米银具有更高的SERS活性；借助于理论计算的甘氨酸酐、甘氨酸的Raman谱对SERS进行了指认，推断出它们在正、负电性纳米银上可能的吸附方式。用微波加热法快速制备出了纳米银溶胶，胶体的颜色随加热时间的增加从淡黄色到深灰色变化。电泳实验、吸收光谱、电镜实验表明，通过控制加热时间、加热方式可控制纳米银的表面电荷以及吸收峰位置、纳米银的形貌。该方法制备的纳米银大都具有较强的SERS活性。在该纳米银上获得极少有报道的氯霉素的Raman光谱，其检测极限为10-5M。用聚乙烯醇和硝酸银以及柠檬酸三钠和硝酸银作为电解液，用电解的方法获得三种胶态纳米银。该纳米银溶胶制备出来时为淡黄色，静置1、2天后，稳定为棕黄色。用电泳实验、吸收谱、电镜、SERS谱对这些纳米银进行了研究。纳米银表面带正电，吸收峰分别为404、421、434nm（聚乙烯醇），电镜实验表明用聚乙烯醇电解液制备的纳米银为多边型粒子，而用柠檬酸电解液制备的为球性粒子。通过SERS研究,结果发现用两种电解液制备的纳米银都具有很强的SERS活性,但聚乙烯醇混合液作为电解液制备的纳米银溶胶具有更广泛的SERS活性。该方法制备的纳米银得到了在正、负电性纳米银及常规方法制备的纳米银得不到的甲基橙的SERS谱。用电解的方法获得了纳米银膜，电镜照片表明纳米银膜上粒子的粒径为70nm，该纳米银膜与便携式Raman光谱仪联用，得到了氯霉素、甲基橙、三聚氰胺、病毒、白叶枯病菌等的SERS谱，且稳定性及可重复性都很好。氯霉素、甲基橙的检测极限与用显微Raman光谱仪的测定结果在同一量级。更多还原

【Abstract】 Surface-Enhanced Raman Spectroscopy (SERS), due to its high sensitivity andlittle interference from water, has served as a valuable tool for those researches,such as surface complexes, surface state of adsorption interface, orientation andconfiguration of biomolecules, analysis of trace organic compounds and drugs, andanalysis of intermediate and final products structures of photochemical reactions.SERS substrate preparation is the most important areas of research in SERS. It hasbecome the pursuit and aim of researchers on finding ways to prepare a highlystable, highly repeatable, highly universal, highly active, simple and inexpensivesubstrate. The main goals in this project are to develop new substrates of nano-silver colloid and film, and to study its properties systematically.Raman spectra of several probe molecules, such as chloramphenicol, methylorange, glycine, glycine anhydride, were computed firstly using quantummechanical ab initio theory and Gaussian’98package. The assignments of Ramanspectrum and SERS of those probe molecules were calculated to obtain informationabout absorption mode and existence forms of probe molecules on surface of nano-silver.Positive and negative nano-silver were prepared and investigated. Sodiumcitrate was used to reduce silver nitrate and obtained the light yellow colored nano-silver colloids; the electrophoresis experiments show that the resulting nano-silveris with positive charge. The absorption spectrum and TEM imaging show that theaverage diameter of the particles is5nm and maximum absorption peaks was398nm for positive nano-silver particles. Tannic acid was used to reduce silver nitrateand obtained the reddish-brown colored nano-silver colloids; the electrophoresisexperiments show that the resulting nano-silver is with negative charge. Theabsorption spectrum and TEM imaging show that the average diameter of theparticles is10nm and maximum absorption peaks is located at418nm. Anionic,cationic, neutral, zwitterionic molecules were used probe molecules to obtain SERSspectrum. The results showed that the positive nano-silver is suitable as a substratefor anionic molecules, and the negative nano-silver is suitable as a substrate forcationic molecules. The negative silver colloids kept at room temperature for two years (for short, old NCS) were compared with the new NCS for absorption spectra,TEM imaging, and SERS spectra. It is found that the NCS, over time, have betterstability and repeatability than the silver colloids prepared by traditional method.The two positive nano-silvers by the same preparation method at different timewere observed by TEM, and it is found that it has good repeatability. Comparedwith the traditionally prepared nano-silver, the positive nano-silver has strongerSERS for probe molecules. The SERS spectrum of glycine anhydride and glycineon positive and negative nano-silver were assigned with the help of the theory ofcalculation of their Raman spectra. The possible adsorption modes of molecules onnano-silver particles were deduced.Nano-silver colloids are prepared by using a microwave heating method. Thecolor of nano-silver changes from light yellow to dark gray when the heat increases.Electrophoresis experiments, absorption spectrum, and electron microscopicobservations show that one can control the nano-silver surface charge, theabsorption peak position, and the morphology of nano-silver by controlling theheating time and heating method,. Most nano-silver prepared by this method has astrong SERS activity. On the nano-silver, Raman spectra of chloramphenicol with adetection limit of10-5M has been obtained.Three kinds of nano-silver colloids were obtained through electrolysis by usingthe mixture solution of polyvinyl alcohol and silver nitrate as electrolyte and themixture solution of sodium citrate and silver nitrate as electrolyte. The resultantlight yellow colored silver colloid turned to brownish yellow after sitting for one ortwo days. Through studying of electrophoresis experiment, absorption spectra, TEMobservation and SERS spectra, it is found that nano-silver surface charge is positiveand absorption peaks are at404,421and434nm (polyvinyl alcohol) respectively.Under electron microscope the nano-silver prepared with polyvinyl alcohol aselectrolyte appeared to be polygon particles, and nano-silver prepared with sodiumcitrate as electrolyte appeared to be spherical particles. Through SERS research, itis found that the nano-silver prepared with the above two types of electrolytes hasstrong SERS activity. Furthermore, the nano-silver colloid that used silver nitratemixing with polyvinyl alcohol solution as electrolyte has the strongest SERSactivity among all the tested molecules. The SERS of methyl orange was obtainedon the nano-silver colloids; it could not have been obtained on the colloids prepared by electrolysis of silver rod using sodium citrate solution and on the silver colloidsprepared by traditional means..A nanoscale silver film was made by electrolysis method, and was studied byscanning electronic microscopy (SEM). The nano-silver particle size is70nm.SERS spectra of chloramphenicol, methyl orange, melamine, viruses, Xanthomonasoryzae and Oryzicola have been obtained using the nanoscale silver film andportable Raman spectrometer. These SERS spectrum have very good stability andrepeatability. The detection limits of Chloramphenicol and methyl orange are in thesame order as using Micro-Raman spectrometer.更多还原