Al2O3薄膜/纳米Ag颗粒复合结构的光吸收谱及增强Raman散射光谱研究

Al₂O₃介质薄膜与纳米Ag颗粒构成的复合结构，被应用于表面增强Raman散射探测实验中，其中Al₂O₃介质薄膜对纳米Ag颗粒的吸收谱及增强Raman散射光谱的影响被特别关注.该复合结构的光学特性表征出纳米Ag颗粒的偶极振荡特性.从光吸收谱中可以看到，其共振吸收谱随Al₂O₃介质薄膜厚度增加而在整个谱域上发生红移，表明纳米Ag颗粒的周围介电常数随Al₂O₃介质薄膜厚度的增加而增大.采用罗丹明6G作为探针原子，6个Raman特征峰的平均增益值作为表征表面增强Raman散射衬底增益程度的量度.实验结果表明,Al₂O₃介质薄膜层的引入提高了纳米Ag颗粒的衬底介电常数，并引起了散射共振的增强，从而使表面增强Raman散射强度提高.

Absorption and surface enhanced Raman scattering spectra caused by combined Ag nanoparticles with Al2O3 dielectric layer

Combined Ag nanoparticles with Al₂O₃ dielectric layer structure have been designed for molecular detection using surface enhanced Raman scattering. Optical absorption spectra studies reveal dipole plasmon resonance absorption property, which show regular red shift with the increasing of the thickness of Al₂O₃ layer. By use the combined structure as SERS substrates and rhodamine 6G as a test molecule, the results in this paper show that the scattering at 1064 nm increases with the thickness of Al₂O₃ dielectric layer which leads to the surrounding dielectric constant of Ag nanoparticles to increase.