表面增强拉曼散射(Surface-enhanced Raman Scattering,SERS)是一种快速且灵敏度高的分子检测技术.拥有高灵敏的、均匀的拉曼信号是光谱技术的必要因素,同时拉曼衬底结构通常也面临复杂的工艺和高昂的成本.为了实现高性能SERS,本文采用多层金-银(Au-Ag)交替沉积、退火和脱合金技术制备多孔Au-Ag复合纳米结构,该方法能用于大面积制备,且制备工艺简便.通过在合适的温度下退火,可以在Au-Ag复合纳米结构表面形成大量纳米孔.这些纳米孔可以牢固地分布在表面形成热点.利用时域有限差分(Finite-difference Time-domain,FDTD)法模拟电场分布,结果表明在Au-Ag复合纳米结构表面可以产生极大的局域场增强效果.实验结果表明SERS检测具有良好的均匀性和高灵敏度.SERS基底检测罗丹明6G(Rhodamine 6G,R6G)分子的增强因子达到2.4×105,相对标准偏差(Relative Standard Deviation,RSD)低至6.9%,对R6G分子的最低检测浓度可达10-11 mol/L.所提出的Au-Ag复合纳米结构及其制备工艺在制备高灵敏度的、高均匀性的SERS基底方面具有很大的潜力.
Preparation of Au-Ag Composite Micro and Nanostructures and High Sensitivity Surface Enhanced Raman Scattering Detection
Surface-enhanced Raman Scattering(SERS)is a rapid and highly sensitive molecular detection technology.Having a highly sensitive and uniform Raman signal is a necessary factor in spectroscopy.Raman substrate structures often face complex processes and high costs.To achieve high-performance SERS,Au-Ag composite nanostructures were prepared by multilayer Au-Ag alternate deposition,annealing and dealloying technology in this research,the method can be used for large-area preparation and facile preparation process.By annealing at a suitable temperature,a large number of nanopores are distributed on the surface of Au-Ag composite nanostructures,which can be firmly distributed on the surface to provide hot spots.The Finite-difference Time-domain(FDTD)method is used to simulate the electric field distribution,and the results show that the Au-Ag composite nanostructure surface can induce great local field enhancement.The experiment results exhibit excellent uniformity and high sensitivity of the SERS detection.The enhancement factor of the Rhodamine 6G(R6G)molecules detected by SERS substrate reaches 2.4×105,and the Relative Standard Deviation(RSD)is as low as 6.9%.The minimum detection concentration of R6G molecules by the Au-Ag composite nanostructures can reach 10-11 mol/L.The proposed Au-Ag composite nanostructures and the fabrication process have great potential in preparation of high sensitivity and excellent uniformity SERS substrate.
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