Au@SiO_2单层膜间耦合效应的表面增强拉曼光谱研究  

Surface Enhanced Raman Spectroscopic Studies on the Coupling Effect of Multilayer Au@SiO_2 Film

作　　者：胡迪君[1,2] 张雪姣[1] 徐敏敏[1] 姚建林[1] 顾仁敖[1] 

机构地区：[1]苏州大学材料与化学化工学部,江苏苏州215123 [2]上海石化工业学校化工科,上海201512

出　　处：《光谱学与光谱分析》2015年第5期1262-1265,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(21073128;21173155)资助

摘　　要：借助水/油两相界面自组装形成致密排列且有序稳定的Au@SiO2单层膜,通过膜层层转移到固相基底的方法制备了具有不同纳米粒子层数的SERS基底,成功在同一硅片上制备了六层Au@SiO2纳米粒子膜,研究了不同膜层数与SERS信号的关系,结合SERS成像技术可测定纳米粒子膜在基底上的层数。通过改变探针分子在多层纳米粒子膜上的位置,研究了纳米粒子膜间的耦合增强效应。研究表明,同一层膜表面探针分子的SERS信号分布均匀,随膜层数的增加,SERS信号明显增强,当膜层达到第五层时探针分子的SERS信号最强,之后几乎保持不变,说明SERS信号主要来源于表层的五层纳米粒子膜,位于五层以下纳米粒子对SERS效应并没有贡献。固定探针分子仅吸附于底层纳米粒子表面,当再覆盖一层裸露纳米粒子膜后,SERS信号达到最大,其主要源于热点的增强作用占主导地位,而覆盖至第三层时,SERS信号反而出现微小减弱,这是由于多层的Au@SiO2纳米粒子膜影响了激发光以及信号的传播,但粒子间产生的耦合效应仍对底层的探针分子起增强作用,当覆盖至五层Au@SiO2膜后,探针分子SERS信号完全消失,由此说明纳米粒子单层膜控制在三层以内可有效检测底层及以上所有纳米粒子上吸附分子的SERS信号,该结果为制备理想SERS基底提供了实验依据。The SiO2 shell with the thickness of 4nm was attached onto high surface enhanced Raman spectroscopy（SERS）active Au core nanoparticles to obtain Au@SiO2core shell nanoparticles by the hydrolysis of sodium silicate solution with the boiling water bath.The inert shell of SiO2 isolated the direct interaction of Au nanoparticles and probe molecules.The stable,compact and uniform monolayer nanoparticles film was self assembled at water/oil interface,and one to six monolayers film was transferred to Si wafer as SERS substrates through layer by layer technique.The relationship between the SERS activities and layers of the monolayer nanoparticles film on Si surface was investigated.The SERS mapping was developed to determine the layers of the [e-mail] coupling effect among the Au@SiO2films was explored by changing the adsorption location of the probe on the multilayer films.The result revealed that the monolayer film was a favourable candidate with high-quality performances for the SERS application.The SERS signal was distributed on the surface with high uniformity at the same monolayer film,and it was enhanced in the intensity with the increase in film layers.It reached the maximun intensity as the film was over five layers.It indicated that the SERS signal was contributed mainly by the first five monolayers.The probe molecules were immobilized onto the first monolayer nanoparticles film,and the SERS signal from the probe approached to the maximum as the second monolayer covered the probe modified first nanoparticles film.It was dominated by the coupling effect（＂hot spots＂）of the adjacent layers.The SERS signal decreased in intensity when the third layer was transferred onto the second layer,and it disappeared after the fouth layer was covered,mainly duo to the shield of the nanoparticles film to the incident laser and Raman signal.The preliminary results provided guidance for fabricating optimal SERS substrates.

关 键 词：Au@SiO2 单层纳米粒子膜 表面增强拉曼光谱 耦合效应 探针 

分 类 号：O657.3[理学—分析化学]