Surface-enhanced infrared absorption (SEIRA) is capable of identifying molecular fingerprints by resonant detection of infrared vibrational modes through the coupling with plasmonic modes of metallic nanostructures. However, SEIRA for on-chip gas sensing is still not very successful due to the intrinsically weak light-matter interaction between photons and gas molecules and the technical challenges in accumulating sufficient gas species in the vicinity of the spatially localized enhanced electric field, namely, the “hot-spots”, generated through plasmonics. In this paper, we present a suspended silicon nitride (Si₃N₄) nanomembrane device by integrating plasmonic nanopatch gold antennas with metal–organic framework (MOF), which can largely adsorb carbon dioxide (CO₂) through its nanoporous structure. Unlike conventional SEIRA sensing relying on highly localized hot-spots of plasmonic nanoantennas or nanoparticles, the device reported in this paper engineered the coupled surface plasmon polaritons in the metal–Si₃N₄ and metal–MOF interfaces to achieve strong optical field enhancement across the entire MOF film. We successfully demonstrated on-chip gas sensing of CO₂ with more than 1800× enhancement factors by combining the concentration effect from the 2.7 μm MOF thin film and the optical field enhancement of the plasmonic nanopatch antennas.

中文翻译：

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表面增强的红外吸收：推动片上气体传感的前沿

表面增强的红外吸收（SEIRA）能够通过与金属纳米结构的等离子体模式耦合来共振检测红外振动模式，从而识别分子指纹。然而，由于光子与气体分子之间固有的弱光物质相互作用以及在空间局部增强电场附近积累足够的气体种类的技术挑战，SEIRA仍无法非常成功地用于片上气体传感。通过等离子体产生的“热点”。在本文中，我们通过将等离激元纳米贴片金天线与金属有机骨架（MOF）集成在一起，提出了一种悬浮的氮化硅（Si ₃ N ₄）纳米膜器件，该器件可以大量吸收二氧化碳（CO ₂）通过其纳米孔结构。与传统的SEIRA感应依赖于等离子纳米天线或纳米粒子的高度局部热点不同，本文报道的设备在金属-Si ₃ N ₄和金属-MOF界面中设计了耦合的表面等离激元极化子，以在整个金属表面上实现强大的光场增强。整个MOF电影。我们结合了2.7μmMOF薄膜的浓度效应和等离子体纳米贴片天线的光场增强，成功地演示了具有超过1800x增强因子的CO ₂的片上气体传感。