Center for Process Analysis and Technology (PA&T), School of Applied Chemistry, Reutlingen University, 72762 Reutlingen, Germany.
Reutlingen Research Institute (RRI), Reutlingen University, 72762 Reutlingen, Germany.
Molecules. 2022 Aug 10;27(16):5097. doi: 10.3390/molecules27165097.
Surface-enhanced Raman spectroscopy (SERS) provides a strong enhancement to an inherently weak Raman signal, which strongly depends on the material, design, and fabrication of the substrate. Here, we present a facile method of fabricating a non-uniform SERS substrate based on an annealed thin gold (Au) film that offers multiple resonances and gap sizes within the same sample. It is not only chemically stable, but also shows reproducible trends in terms of geometry and plasmonic response. Scanning electron microscopy (SEM) reveals particle-like and island-like morphology with different gap sizes at different lateral positions of the substrate. Extinction spectra show that the plasmonic resonance of the nanoparticles/metal islands can be continuously tuned across the substrate. We observed that for the analytes 1,2-bis(4-pyridyl) ethylene (BPE) and methylene blue (MB), the maximum SERS enhancement is achieved at different lateral positions, and the shape of the extinction spectra allows for the correlation of SERS enhancement with surface morphology. Such non-uniform SERS substrates with multiple nanoparticle sizes, shapes, and interparticle distances can be used for fast screening of analytes due to the lateral variation of the resonances within the same sample.
表面增强拉曼光谱（SERS）为固有微弱的拉曼信号提供了强烈的增强，这强烈依赖于基底的材料、设计和制造。在这里，我们提出了一种基于退火薄金（Au）膜的简单方法来制造非均匀 SERS 基底，该基底在同一样品中提供了多个共振和间隙尺寸。它不仅具有化学稳定性，而且在几何形状和等离子体响应方面也表现出可重复的趋势。扫描电子显微镜（SEM）显示出具有不同间隙尺寸的颗粒状和岛状形态，位于基底的不同横向位置。消光谱显示，纳米粒子/金属岛的等离子体共振可以在整个基底上连续调谐。我们观察到，对于分析物 1,2-双（4-吡啶基）乙烯（BPE）和亚甲蓝（MB），最大的 SERS 增强在不同的横向位置实现，消光谱的形状允许将 SERS 增强与表面形态相关联。由于同一样品中共振的横向变化，具有多种纳米粒子尺寸、形状和粒子间距离的这种非均匀 SERS 基底可用于分析物的快速筛选。
