Au@PS阵列SERS基底的特性研究

Study on SERS substrate properties ofAu@PS arrays

表面增强拉曼散射(Surface-enhanced Raman scattering,SERS)是一种高效快速的物质检测方法。其检测灵敏度高,有效地克服了常规拉曼散射信号弱难以得到推广应用的问题。研究SERS基底的结构及特性有助于理解增强机理,同时也为制备高性能的SERS基底奠定基础。本文以旋涂自组装的聚苯乙烯(PS)胶体球为基本结构,采用离子溅射镀膜的方式制备了Au@PS阵列结构的SERS基底。通过调整膜层厚度实现对球结构大小及间隙的调控,进而研究该种SERS基底在不同膜层厚度下的增强性能及表面形貌特征。扫描电镜图显示,当膜层厚度为50nm时,膜层外表面形成了明显的金颗粒;以罗丹明6G为探针分子,对制备的SERS基底进行拉曼表征,结果表明,膜层厚度50nm的SERS基底增强效果最强,对R6G溶液的检测极限达到了10-9mol/L;另外,采用FDTD软件对制备的SERS基底进行了电磁场仿真,仿真发现,强电磁场分布在球体间隙及金颗粒附近,同时发现,膜层厚度为50nm的模型电磁场强度最强,该结果与拉曼表征实验的结果一致。

Surface-enhanced Raman scattering(SERS)is an efficient method for substance detection.Unlike conventional Raman scattering,whose signal is too weak to be detected,SERS has been widely used in many applications due to its superior merits of high sensitivity.Priori knowledge of SERS substrate characteristics contributes to improve the performance of the prepared SERS substrate.In this paper,SERS substrate on the basis of Au@PS array was prepared using lon sputtering coating.The size and clearance of the sphere were controlled by adjusting the coating thickness.Performance and surface features of a variety of SERS substrates with different coating thickness were studied.SEM results indicate that gold particles on the outside surface membrane layer are obviously visible when the coating thickness is 50 nm.Subsequently,Raman characteristics of the prepared substrate were valued by using Rhodamine 6G.Results show that the SERS substrate with a coating thickness of 50 nm has the strongest enhancement effect.Simulations were also carried out to get a better knowledge of the electromagnetic field distribution within the prepared SERS substrate.Results of FDTD simulation show that the electromagnetic of the clearance and field near the gold particles is strong.And meanwhile,the intensity of the electromagnetic field is the strongest when the coating thickness is equal to 50 nm,which is in agreement with the experimental results.