Niu Zhiqiang, Fang Yan
Beijing Key Lab for Nano-Photonics and Nano-Structure, Department of Physics, Capital Normal University, Beijing 100037, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2007 Mar;66(3):712-6. doi: 10.1016/j.saa.2006.04.021. Epub 2006 May 4.
Surface-enhanced Raman scattering (SERS) spectrum of very good quality of "silver nano-particles/sample molecules/silver film" system was reported by nesting the sample molecules to the gap of silver nano-particles and silver film, indicating that "silver nano-particles/sample molecules/silver film" is a highly SERS-active system. Not only was the number of the vibrational modes increased, but also were the frequencies of Raman bands up and down shifted. It is difficult to separate the contributions of the electromagnetic and chemical mechanisms to the great enhancement of the Raman signal. The shift by 5-30cm(-1) of the SERS bands and the change in their relative intensity compared with the ordinary Raman spectrum indicate the chemisorption of the sample molecules on the silver-modified silver surface. Furthermore, the silver nano-particles modified on the rough silver film surface play an important role in magnifying the surface local electric field near the silver surface through resonant surface plasmon excitation. From the rich information, obtained from high-quality SERS of PHBA in ternary system, we inferred that PHBA molecules in ternary system adsorb onto the metal surfaces through carboxyl at a perpendicular orientation.
通过将样品分子嵌入银纳米颗粒与银膜的间隙中，报道了“银纳米颗粒/样品分子/银膜”体系具有高质量的表面增强拉曼散射（SERS）光谱，这表明“银纳米颗粒/样品分子/银膜”是一个具有高SERS活性的体系。不仅振动模式的数量增加了，拉曼谱带的频率也发生了上下移动。很难区分电磁机制和化学机制对拉曼信号大幅增强的贡献。与普通拉曼光谱相比，SERS谱带位移5 - 30cm⁻¹及其相对强度的变化表明样品分子在银修饰的银表面发生了化学吸附。此外，粗糙银膜表面修饰的银纳米颗粒通过共振表面等离子体激元激发，在放大银表面附近区域的表面局部电场方面发挥着重要作用。从三元体系中PHBA的高质量SERS获得的丰富信息，我们推断三元体系中的PHBA分子通过羧基以垂直取向吸附在金属表面。
