中文摘要：

在Fe_3O_4存在下,以聚乙烯吡咯烷酮（PVP）为分散剂和还原剂,利用简单的一步法制备了Fe_3O_4@SiO_2/Ag纳米复合材料。所制得的Fe_3O_4@SiO_2/Ag纳米复合物对罗丹明B（RhB）具有较好的表面拉曼光谱增强（SERS）效果,可以用作SERS基底。二氧化硅作为贵金属Ag纳米颗粒的载体,不仅可以起到分散贵金属的作用,还可以稳定金属相,更好地吸附RhB,使SERS效应得以稳定,可用于痕量检测,其检测极限可达1×10~（-12）mol/L。此外,该材料具有较好的磁性,方便回收再利用。该复合材料制备方法简便易行、条件温和,为合成其他纳米复合材料提供了启示。

英文摘要：

By using PVP as the dispersant and reducing agent,Fe_3O_4@SiO_2/ Ag nanocomposites are synthesized via a simple and one-step method in the present of Fe_3O_4. The nanocomposites are acted well as a SERS-active substrates for Rh B. TheSiO_2 shell between Fe_3O_4 nanoparticles and Ag nanoparticles is used to avoid the agglomeration of Ag nanoparticles and stabilize metal phase. The unique Raman enhancement effect of Fe_3O_4@SiO_2/ Ag substrates indicates that Rh B can be detected at a concentration as low as 1 × 10~（-12） M. Furthermore,the super paramagnetic property of Fe_3O_4 facilitates the efficient recycling of products with the assistance of an external magnetic field. This synthetic method provides a revelation for the preparation of other nanocomposites.