Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for trace-level fingerprinting. Recently, layered two-dimensional (2D) materials have gained significant interest as SERS substrates for providing stable, uniform, and reproducible Raman enhancement with the potential for trace-level detection. Yet, the development of effective 2D SERS substrates is still hindered by the lack of fundamental understanding of the coupling mechanism between target molecules and substrates. Here, we report a systematic excitation-dependent Raman spectroscopy investigation on the coupling between 2D materials such as SnS₂, MoS₂, WSe₂, and graphene and small organic molecules like rhodamine 6G (Rh 6G). Strong coupling between SnS₂ and Rh 6G is found due to their degenerate excitons through Raman excitation profiles (REP), leading to the enhancement of Rh 6G vibrational modes that are observable down to 10⁻¹³M. Our study shows that exciton coupling in the substrate-adsorbate complex plays a vital role in the Raman enhancement effect, opening a new route for designing SERS substrates for high sensitivity.

表面增强拉曼光谱 (SERS) 是一种强大的痕量指纹识别技术。最近，层状二维 (2D) 材料作为 SERS 基底引起了人们的极大兴趣，因为它可以提供稳定、均匀和可重复的拉曼增强，并具有痕量级检测的潜力。然而，由于缺乏对目标分子和基底之间耦合机制的基本了解，有效的二维 SERS 基底的开发仍然受到阻碍。在这里，我们报告了对 SnS ₂、 MoS ₂、 WSe ₂和石墨烯等二维材料与罗丹明 6G (Rh 6G) 等有机小分子之间耦合的系统性激发相关拉曼光谱研究。 SnS ₂和 Rh 6G之间的强耦合是由于它们通过拉曼激发剖面 (REP) 的简并激子而发现的，从而导致在低至 10 ^-13 M 处可观察到的 Rh 6G 振动模式的增强。我们的研究表明，SnS 2 和 Rh 6G 中的激子耦合基质-吸附物复合物在拉曼增强效应中发挥着至关重要的作用，为设计高灵敏度的SERS基质开辟了新途径。