摘要
以CTAB表面活性剂胶束为模板用化学还原法制备出含有银纳米棒的银胶体,用透射电镜(TEM)对颗 粒形貌进行了表征.UV Vis吸收谱显示,含银纳米棒溶胶有两个吸收蜂,其中长波长吸收峰位置随胶粒长径比增 加迅速红移和宽化.用多尺寸统计平均的Mie散射模型计算了纳米棒银胶体的吸收谱,较好地解释了长波长吸收 峰的宽化.以此胶体为衬底材料,测量了染料分子的表面增强拉曼散射(SERS),结果显示,SERS强度随胶体中 所含纳米棒长径比的增加呈现先显著增强后缓慢减弱的变化规律,用电磁增强理论对有关现象进行了分析.
The colloids containing silver nanorods were prepared by chemical reduction using CTAB surfactant as the template and were characterized by TEM. UV-visible absorption spectra show that the Ag nanorods have two absorption bands and the long-wavelength band shifts to red evidently with the increase of aspect ratio. The statistical average for the Mie scattering by small silver spheroids was used to simulate the UV-visible absorption spectra, showing that the broadening of the long-wavelength absorption band is due to the shape inhomogeneity of the silver nanorods. With the prepared Ag nanorod colloids as substrates, SERS of 1-ethyl-3'-methyl-2-thiacyanine was recorded. It was shown that, with the increase of aspect ratio of the nanorods, the intensities of SERS increase evidently at first and then reduce gradually. The dependence of SERS intensities with the aspect ratio was attributed to the cooperation of the plasma resonance mechanism and the 'lightning-rod effect' of the silver nanorod particles.
基金
ProjectsupportedbytheNationalNaturalScienceFoundationofChina(20173051
29873043)andtheNaturalScienceFoundationofAnhuiProvincial(01046302)
