新型金属复合纳米结构的制备及其表面增强拉曼散射效应

Since surface enhanced Raman scattering was discovered it has become a high surface-sensitivity research tool in surface science and nanoscience; Raman enhanced substrates are directly related to Raman enhancement effect, while the traditional Raman enhanced substrates have the disadvantages such as poor repeatability, low uniformity and disordered arrangement which restrict further research and the wide application of the Raman strengthening mechanism. The project puts forward the solid-state ionics method to prepare silver nanowire arrays, copper nanowire arrays, gold nanowire arrays and silver nanostructures, silver/copper composite nanostructures with high surface roughness to obtain new metal composite nanostructures Raman enhanced substrates combining gold nanoparticles surface modification technique. Exploring the dependency relationship between the enhancement effect and nanostructure parameters(such as nanowire diameter, surface roughness and ordered arrangement). The Raman enhancement mechanism of action of nano active substrate is revealed. The influence rule of the parameters such as external electric field, ion beam density, substrate temperature and ion conducting memtrane thickness on metal nanostructures in the growth process of metal nanostructures are studied systematically and the degree of order and pattern of metal nanostructures is controlled accurately. The achievement of the project can expound the physical mechanism which increases the enhancement effect of local surface field on nano active substrate and provide theoretical support on developing repeatable and stable trace detection technology of Raman spectrum.

表面增强拉曼散射自发现以来已经成为表面科学乃至纳米科学中具备高表面灵敏度的研究工具；拉曼增强基底直接关系着拉曼增强效应，然而传统的拉曼增强基底重复性差、均匀性差、排列无序等缺点限制了拉曼增强机理的深入研究和广泛应用。本项目拟采用“固态离子学方法”制备有序银、铜、金纳米线阵列及具有高表面粗糙度的银纳米结构和银铜复合纳米结构，同时结合金纳米颗粒表面修饰技术，以此设计和制备新型金属复合纳米结构拉曼增强基底，探索其增强效应与纳米结构参数（如纳米线直径、表面粗糙度、排列有序度等）之间的依赖关系；揭示纳米活性基底的拉曼增强作用机理；系统研究金属纳米结构生长过程中的外加电场强度、离子流密度、基底温度、导离子膜厚度等参数对金属纳米结构的影响规律，实现金属纳米结构形貌和有序度的精确控制。本项目的完成可阐明提高纳米活性基底表面局域场增强效应的物理机理，并为发展可重复和稳定的拉曼光谱痕量检测技术提供理论支持。

随着纳米科技的快速发展，表面增强拉曼散射(SERS)被赋予了新的发展动力。SERS基底存在的排列无序、重复性和均匀性差等缺点，限制了深入研究SERS增强机理及其技术的广泛应用。. 选取具有高离子电导率的快离子导体RbAg4I5薄膜和Rb4Cu16Cl13I7薄膜，利用固态离子学方法在不同外加电流作用下分别制备了厘米级银、铜和金纳米结构，铜金和银铜合金纳米线及银铜金复合纳米线。利用扫描电子显微镜（SEM）观测金属纳米结构的表面形貌、利用能量色散光谱仪（EDS）测量金属纳米结构的化学成分并选取罗丹明6G水溶液作为检测拉曼增强性能的探针分子，利用拉曼光谱仪测量金属纳米结构基底的拉曼增强能力。结果表明，外加电流为4μA时生成稀疏的有序排列银纳米线阵列，纳米线直径分布为80-100纳米。制备的铜纳米结构宏观和微观均为树枝状，最长长度为5厘米，直径为30-100纳米，分形维数为1.34，检测罗丹明6G的极限浓度为10-12 mol/L。金纳米线呈竹节状，直径分布为40-90纳米，检测罗丹明6G的极限浓度为10-17 mol/L。铜金合金纳米线直径分布为40-100纳米，铜与金的摩尔比为16:1，检测罗丹明6G的极限浓度为10-15 mol/L。长程有序、短程有序银铜合金纳米线直径分布为30-130纳米，银与铜的摩尔比为15:1，检测罗丹明6G的极限浓度为10-14mol/L。长程有序、短程有序银铜金复合纳米线最长长度为1厘米并呈竹节状生长，表面粗糙度较高，直径分布为60-100纳米，银、铜与金的摩尔比为15:2:1，检测罗丹明6G的极限浓度为10-16 mol/L。. SERS基底直接影响其增强效应，具有高增强能力、高均匀性和可重复性的SERS活性基底将得到关注与发掘。