Abstract A recent surge of interest in surface-enhanced Raman scattering (SERS) has stimulated the search for new systems that can be utilized to fabricate high-performance optical devices. However, the two-dimensional design of the vast majority of SERS-based assemblies has significantly hindered their real-life applicability, motivating the development of three-dimensional volumetric materials. Here, we report selective SERS observed in a volumetric Bi2O3-Ag eutectic composite obtained by the micro-pulling-down method utilizing directional solidification of eutectics. The enhancement of the Raman signal originates from the localized surface plasmon resonance, LSPR, resulting from silver nanoparticles embedded in the composite. The plasmonic origin of the enhancement is confirmed by characteristic features, such as (i) an enhancement magnitude >103, (ii) the correspondence between the Raman bands’ intensity upon excitation by different wavelengths and the localized surface plasmon resonance (LSPR) intensity, and (iii) the occurrence of overtones, which are absent in the as-grown material that does not exhibit LSPR. The examined Bi2O3-Ag eutectic-based composite is obtained by directional solidification using a simple crystal growth technique. It is the first case of a bulk SERS-active material fabricated by crystal growth techniques, which opens new perspectives towards scalable three-dimensional optical elements with tunable properties based on Raman scattering.

中文翻译：

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体纳米等离子体 Bi2O3-Ag 共晶复合材料中的选择性表面增强拉曼散射

摘要 最近对表面增强拉曼散射 (SERS) 的兴趣激增刺激了对可用于制造高性能光学器件的新系统的研究。然而，绝大多数基于 SERS 的组件的二维设计严重阻碍了它们在现实生活中的适用性，推动了三维立体材料的发展。在这里，我们报告了在通过利用共晶定向凝固的微下拉法获得的体积 Bi2O3-Ag 共晶复合材料中观察到的选择性 SERS。拉曼信号的增强源于局部表面等离子体共振，LSPR，由嵌入复合材料中的银纳米粒子产生。增强的等离子体起源由特征特征证实，例如（i）增强幅度> 103，（ii）不同波长激发后的拉曼带强度与局域表面等离子体共振（LSPR）强度之间的对应关系，以及（iii）泛音的出现，这些都不存在在未表现出 LSPR 的生长材料中。所检测的 Bi2O3-Ag 共晶复合材料是使用简单的晶体生长技术通过定向凝固获得的。这是通过晶体生长技术制造的块状 SERS 活性材料的第一个案例，为基于拉曼散射的具有可调特性的可扩展三维光学元件开辟了新的视角。(iii) 泛音的出现，这在未表现出 LSPR 的原始材料中是不存在的。所检测的 Bi2O3-Ag 共晶复合材料是使用简单的晶体生长技术通过定向凝固获得的。这是通过晶体生长技术制造的块状 SERS 活性材料的第一个案例，为基于拉曼散射的具有可调特性的可扩展三维光学元件开辟了新的视角。(iii) 泛音的出现，这在未表现出 LSPR 的原始材料中是不存在的。所检测的 Bi2O3-Ag 共晶复合材料是使用简单的晶体生长技术通过定向凝固获得的。这是通过晶体生长技术制造的块状 SERS 活性材料的第一个案例，为基于拉曼散射的具有可调特性的可扩展三维光学元件开辟了新的视角。