Kong Lingbo, Lee Changwon, Earhart Christopher M, Cordovez Bernardo, Chan James W
Opt Express. 2015 Mar 9;23(5):6793-802. doi: 10.1364/OE.23.006793.
We experimentally demonstrate the integration of near-field optical tweezers with surface enhanced Raman scattering (SERS) spectroscopy by using the optical evanescent wave from a silicon nitride waveguide to trap single shell-isolated metallic nanoparticles (NPs) and simultaneously excite SERS signals of Raman reporter molecules adsorbed on the surface of the trapped metallic NPs. Both evanescent wave excited Stokes and anti-Stokes SERS spectra of waveguide trapped single silver (Ag) NPs were acquired, which were compared to their far-field SERS spectra. We investigated the trapping of bare and shell-isolated metallic NPs and determined that the addition of a shell to the metallic NPs minimized particle-induced laser damage to the waveguide, which allowed for the stable acquisition of the SERS spectra. This work realizes a new nanophotonic approach, which we refer to as near-field light scattering Raman (NLS-Raman), for simultaneous near-field optical trapping and SERS characterization of single metallic NPs.
我们通过使用来自氮化硅波导的光学倏逝波来捕获单个壳层隔离的金属纳米颗粒（NP），并同时激发吸附在捕获的金属NP表面的拉曼报告分子的表面增强拉曼散射（SERS）信号，通过实验证明了近场光镊与SERS光谱的集成。获取了波导捕获的单个银（Ag）NP的倏逝波激发的斯托克斯和反斯托克斯SERS光谱，并将其与远场SERS光谱进行了比较。我们研究了裸金属NP和壳层隔离金属NP的捕获情况，并确定在金属NP上添加壳层可将颗粒诱导的激光对波导的损伤降至最低，从而能够稳定地获取SERS光谱。这项工作实现了一种新的纳米光子学方法，我们将其称为近场光散射拉曼（NLS-拉曼），用于单个金属NP的同时近场光学捕获和SERS表征。
