混合溶胶表面增强拉曼散射的活性异常研究

研究了两组混合溶胶的表面增强拉曼散射（SERS）活性的变化,分别为柠檬酸钠还原法制备的银溶胶和金溶胶混合态与硼氢化钠还原法制备的银溶胶和金溶胶混合态.利用透射电镜表征溶胶混合前后的形态,紫外可见光谱分析其混合过程中吸收峰的变化,以碱性品红为探针分子对混合溶胶的SERS活性进行表征.结果表明,当银溶胶与金溶胶达到一定比例混合时,其拉曼散射活性会得到异常增强,增强倍数可达到10~20倍,但对于不同还原方法制备的溶胶,最大增强时的银/金比例并不相同.这种增强不同于卤素离子引起的溶胶SERS的共振增强,应该属于物理增强的一种,与最终的溶胶-分子体系的凝聚态有关.

Study on High Surface Enhanced Raman Scattering Activity of Mixed Colloids

The SERS activity of two groups of mixed colloids was studied.One group of the mixed colloids was prepared by the sodium citrate-induced reduction and the other was prepared by the sodium borohydride-induced reduction.By means of transmission electron microscopy（TEM）,we characterized the morphologies of the colloids,including pure colloids and mixed colloids.The change of absorption peak was observed by UV-vis absorption spectroscopy.Fuchsin Basic（FB） was used as the probe molecule to study SERS activity of the colloids.The results showed the SERS activity was enhanced 10-20 times in mixed colloids when the ratio between the silver colloid and the gold colloid reached an appropriate proportion.But the ratio was not constant when the preparation method changed.The enhancement was different with the resonance enhancement produced by halogen ion.It was one sort of the physical enhancement and was related with the aggregation morphologies of the colloid-molecule system.