基于单个花状银纳米颗粒的表面增强拉曼散射效应研究

Surface-enhanced Raman Scattering Study of Individual Flower-like Silver Nanoparticles

在室温下,以硝酸银为银源,抗坏血酸为还原剂,通过调节表面活性剂聚乙烯吡络烷酮的浓度,实现对花状银纳米颗粒的可控制备。利用扫描电子显微镜、原子力显微镜、X射线衍射和X射线能谱等手段检测并分析了材料的形貌结构和成分组成。实验结果表明,当聚乙烯吡络烷酮的浓度为0.1 mol/L时,所制备花状银纳米颗粒的表面结构达到最精细的状态且颗粒的尺寸达到微米量级,适合对单颗粒进行定位与光学性质研究。以结构最优化的花状银纳米颗粒为表面增强拉曼散射基底材料,以羟基苯甲酸为探针,对单个和少数颗粒的表面增强拉曼散射效应进行了研究,并借助暗场散射光谱分析了基底的表面增强拉曼散射机理。结果显示,该花状银纳米颗粒因其独特的表面结构为拉曼信号增强提供了大量“热点”。良好的拉曼性能以及较低的制备成本表明,该新型表面增强拉曼散射基底具有很大的应用前景。

Flower-like silver nanoparticles are well-controlled synthesized at room temperature by using silver nitrate as silver precursor,ascorbic acid as reductant and polyvinyl pyrrolidone with different concentrations as surfactant.Their structure and elemental composition are characterized by scanning electronic microscopy,atomic force microscope,X-ray diffraction and energy dispersive X-ray spectroscopy.When the concentration of polyvinyl pyrrolidone is up to 0.1 mol/L,the finest surface structure of the prepared flower-like silver nanoparticles is obtained,and the size of the particles reaches micron scale,which is suitable for the location and optical property study of single particles.The surface-enhanced Raman scattering(SERS)activity of individual and a few structure-optimized flower-like silver nanoparticle substrates are investigated using p-hydroxybenzoic acid as probes.The SERS mechanism of the substrates is analyzed by mean of dark field scattering spectroscopy.The experimental results indicate that the special surface structures of the flower-like silver nanoparticles provide large quantities of“hot spots”for the enhanced Raman intensity.The satisfying SERS properties combined with low synthesis costs show the prospective application possibilities of this novel SERS substrate.