复合Ag/SiO_2正弦光栅基底SERS特性分析

SERS characteristics analysis of composite Ag/SiO_2 sinusoidal grating

当前微流控表面增强拉曼散射(SERS)检测领域常用的贵金属纳米颗粒溶胶单位体积内热点区域数量有限且热点区域范围较小,而贵金属纳米三维阵列结构加工时间长,成本高昂并存在"记忆效应"。本文提出了集成到微流道的复合Ag/SiO_2正弦光栅SERS基底结构,可以利用激光干涉光刻技术进行制备,无需预制掩膜版,可实现大面积、低成本SERS基底简易快速制备。利用严格耦合波分析方法(RCWA)建立了复合正弦光栅表面电场增强数学评估模型,推导了表面等离子体共振(SPP)耦合吸收率数学模型,分析了入射光、复合正弦光栅结构与外界环境介电常数的优化匹配关系,得到了入射光785 nm条件下的最佳复合正弦光栅结构。通过制备加工并实验验证了复合正弦光栅的SERS性能,SERS增强因子(EF)能够达到10~4。

In current microfluidic-SERS(surface-enhanced Raman scattering)detection fields,noble metal nanoparticle sols are commonly used but a limited number of hot spots exist per unit of its volume and the areas of these hot spots are very small.Another common SERS substrate,the noble metal nano-three-dimensional array,has a time-consuming fabrication process and is costly to manufacture,while also succumbing to the memory effect.In this paper,a composite Ag/SiO 2 sinusoidal grating SERS substrate structure integrated into a microchannel is proposed,which can be fabricated by laser interference photolithography and has no need for prefabricated photomasks.Large area and low-cost SERS substrates can be created simply and rapidly by using this method.The mathematical evaluation model of electric field enhancement near the composite sinusoidal grating surface is established with rigorous coupled wave analysis(RCWA).The mathematical model of the surface plasmon polaritons(SPP)coupling absorption is derived.The optimization matching relation of incident light,the composite sinusoidal grating structure and the dielectric constant of the external environment are analyzed.The optimal composite sinusoidal grating structure was obtained when the wavelength of incident light was 785 nm.The composite sinusoidal grating was prepared and its SERS performance was verified experimentally,proving that the SERS enhancement factor(EF)can reach 10^4.