表面等离子激元非线性表面增强拉曼散射效应

本文采用热蒸发法制备得到纳米Ag颗粒作为增强拉曼衬底, 利用入射光子与纳米颗粒表面价电子的相互作用机理, 激发出高能表面等离子激元, 其表面等离子形成的高能"热点"起到表面增强拉曼散射效果. 通过比较不同入射光强下的拉曼峰强, 指出纳米Ag颗粒的增强拉曼散射效果可以实现低探测光强下的高散射强度, 即纳米Ag颗粒的表面等离子激元具有非线性的表面增强拉曼散射效果, 可降低对样品的光、热损伤, 以利于拓展拉曼散射光谱的应用范围. 同时比较不同纳米Ag颗粒衬底的表面增强拉曼散射效果表明, 采用的热蒸发工艺具有较大的工艺域度, 具有较强的工艺兼容性.

Nonlinear phenomenon of surface enhanced Raman scattering caused by surface plasmon

Silver nanoparticles are synthesized through thermal evaporation for molecular detection using surface enhanced Raman scattering microscopy. The optical properties of silver nanoparticles are obtained by ultraviolet-visible spectrometry, which show the resonance wavelength near the detecting wavelength of Raman scattering (488 nm). Using rhodamine 6G as a test molecule, the results in this paper show that the detected Raman peak intensity has a nonlinear relationship with the incident power density when surface plasmon of silver nanoparticles was excitated by incident photon. This nonlinear phenomenon of surface enhanced Raman scattering caused by "hot spot" with high electromagnetic field strength provides an effective way to obtain high scattering intensity without high incident power density, which may expand the scope of Raman scattering application.