Schultz Zachary D, Wang Hao, Kwasnieski Daniel T, Marr James M
Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, IN USA 46556-5670.
Proc SPIE Int Soc Opt Eng. 2015 Aug 9;9554. doi: 10.1117/12.2189674.
Enhanced Raman scattering from plasmonic nanostructures associated with surface enhanced (SERS) and tip enhanced (TERS) is seeing a dramatic increase in applications from bioimaging to chemical catalysis. The importance of gap-modes for high sensitivity indicates plasmon coupling between nanostructures plays an important role. However, the observed Raman scattering can change with different geometric arrangements of nanoparticles, excitation wavelengths, and chemical environments; suggesting differences in the local electric field. Our results indicate that molecules adsorbed to the nanostructures are selectively enhanced in the presence of competing molecules. This selective enhancement arises from controlled interactions between nanostructures, such as an isolated nanoparticle and a TERS tip. Complementary experiments suggest that shifts in the vibrational frequency of reporter molecules can be correlated to the electric field. Here we present a strategy that utilizes the controlled formation of coupled plasmonic structures to experimentally measure both the magnitude of the electric fields and the observed Raman scattering.
与表面增强拉曼散射（SERS）和针尖增强拉曼散射（TERS）相关的等离子体纳米结构的增强拉曼散射在从生物成像到化学催化等应用中正在急剧增加。间隙模式对于高灵敏度的重要性表明纳米结构之间的等离子体耦合起着重要作用。然而，观察到的拉曼散射会随着纳米颗粒的不同几何排列、激发波长和化学环境而变化；这表明局部电场存在差异。我们的结果表明，在存在竞争分子的情况下，吸附到纳米结构上的分子会被选择性增强。这种选择性增强源于纳米结构之间的可控相互作用，例如孤立的纳米颗粒和TERS针尖。补充实验表明，报告分子振动频率的变化可以与电场相关联。在此，我们提出一种策略，该策略利用耦合等离子体结构的可控形成来通过实验测量电场强度和观察到的拉曼散射。
