Since localized surface plasmon (LSP) is capable of generating strong electromagnetic fields, it has achieved extensive applications in surface-enhanced Raman scattering (SERS). As opposed to this, surface plasmon polariton (SPP) has been rarely employed for its weak electric field enhancement. The present study proposed an Ag nanoparticles (AgNPs) and multilayer Au/Al₂O₃ film (MLF) hybrid system, acting as an efficient SERS substrate by coupling LSPs and SPPs resonances. The dispersion relationship indicates that the light scattered by the AgNPs excites the SPP in the MLF, while the electric field is bound to the Au/Al₂O₃ interface and is significantly enhanced. As revealed from the simulated results, SPPs were generated in the MLF and then coupled with each other to generate a bulk plasmon polariton (BPP). As impacted by BPP, the electric fields stimulated by LSP displayed a dramatic increase. Besides, the electric field exhibited increased intensity with the layer of film. As rhodamine 6G (R6G) and malachite green (MG) were employed as the probe molecules, the AgNPs/MLF hybrid structure demonstrated highly sensitive SERS performance, complying with the theoretical simulations. Specific to the mentioned SERS substrate, R6G and MG had the limit of detection of 1.2 × 10⁻¹⁰M and 7.9 × 10⁻⁹M, respectively, demonstrating the prominent prospects of the NPs/MLF hybrid structure in SERS.

中文翻译：

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表面增强拉曼散射的粒子-多层膜系统中多种等离子体极化模式的耦合

由于局部表面等离激元（LSP）能够产生强电磁场，因此已在表面增强拉曼散射（SERS）中获得了广泛的应用。与此相反，表面等离子体激元（SPP）由于其弱电场增强作用而很少被采用。本研究提出了一种银纳米颗粒（AgNPs）和多层Au / Al ₂ O ₃薄膜（MLF）杂化系统，通过耦合LSP和SPP共振作为有效的SERS衬底。色散关系表明，AgNPs散射的光激发了MLF中的SPP，而电场则结合到Au / Al ₂ O _3上界面并得到了显着增强。从模拟结果中可以看出，SPP在MLF中生成，然后彼此耦合以生成体等离子体激元极化（BPP）。受BPP的影响，LSP激发的电场急剧增加。此外，电场随着膜层显示出增加的强度。由于罗丹明6G（R6G）和孔雀石绿（MG）被用作探针分子，AgNPs / MLF杂化结构表现出高度敏感的SERS性能，符合理论模拟。对于上述SERS底物而言，R6G和MG的检出限分别为1.2×10 ^-10 M和7.9×10 ^-9 M，证明了SERS中NPs / MLF杂化结构的突出前景。