树枝状银微纳结构的表面增强拉曼散射效应研究

摘要

利用两电极电化学沉积法制备出一种树枝状银微纳结构基体.扫描电子显微镜(SEM)的表征结果证实所制备的银基体呈现出完整的树枝状结构,具有对称性的树枝和树干,且树叶清晰可见.实验结果表明,树枝状银微纳结构的表面增强拉曼散射(Surface-enhanced Raman scattering,SERS)可以检测到超低浓度的罗丹明6G(Rhodamine 6G,R6G,10-10 mol/L)光谱信号,即树枝状银微纳结构作为SERS基体表现出较好的灵敏性;当R6G的浓度在10-5~10-10 mol/L范围依次降低一个数量级时,谱带610 cm-1处的拉曼散射强度的相对标准偏差分别为12.1%,12.0%,11.7%,10.9%,13.2%和14.3%,表明所制备银基体的SERS"热点"(Hot spots)分布较均一,树枝状银微纳结构作为SERS基体具有较好的重现性;当低SERS活性的3-巯基丙酸(3-Mercaptopropionic acid,3MPA)的检测浓度为10-5 mol/L时,利用树枝状银基体能检测到3MPA的SERS光谱,说明所制备的银基体对低活性物质也具有较好的SERS灵敏性.%The facile and efficient synthetic route for Ag dendritic nanostructures on Indium tin oxide ( ITO) via electrodeposition was reported. The results showed that the Raman intensities of rhodamine 6G ( R6G) decreased with decreasing the loading concentration, and even at a low concentration of 10-10 mol/L, the signatures of R6G in Raman spectrum were still clearly observed. It indicated that the Ag dendritic nanostructures exhibited high surface-enhanced Raman scattering ( SERS) sensitivity. Moreover, the relative standard deviation ( RSD ) of band at 610 cm-1 was calculated to be 12 . 1%, 12 . 0%, 11 . 7%, 10 . 9%, 13. 2% and 14. 3%, respectively, corresponding with the concentration of R6G from 10-5 mol/L to 10-10 mol/L, which revealed that the Ag dendritic nanostructures could provide abundant hot spots and exhibited excellent reproducibility. In addition, the SERS spectrum of 3-mercaptopropionic acid (3MPA) also could be detected when its concentration was 10-5 mol/L. This method offers an easy and low-cost way to prepare Ag dendritic substrates and makes SERS detection more practicable.