Najem Melissa, Carcenac Franck, Coutaud Luka, Mouhibi Mohamed, Taliercio Thierry, Gonzalez-Posada Fernando
University of Montpellier, Institut d'Electronique et des Systèmes, Montpellier, Occitanie, France.
CNRS Laboratory for Systems Analysis and Architecture, Toulouse, Occitanie, France.
Nanophotonics. 2023 Apr 10;12(12):2199-2212. doi: 10.1515/nanoph-2023-0131. eCollection 2023 Jun.
Surface-enhanced infrared absorption (SEIRA) spectroscopy is a competent method to detect trace quantity of molecules and even protein conformational flexibility by enhancing their vibrational modes. To improve the spectroscopy features, we propose a surface with honeycomb-like (HC) arrangement of aluminum equilateral triangles within a metal-insulator-metal configuration. With adjustable geometric parameters, the HC nanoantennas allow a tunable and wide spectral coverage in the IR. The reflectance measurements correlate extremely well with the numerical simulations. Being compact and insensitive to the light polarization, the HC are appealing for boosting the signal-to-noise ratio and increasing the number of hotspots as required for sensing applications. These nanoantennas are thus suitable for accurate and broadband SEIRA sensing via a spectral overlap between the large plasmonic resonances and the narrow IR vibrational modes of our analyte (vanillin). In line with our previously studied bowties nanoantennas, we demonstrate, using HC, SEIRA enhancement factors greater than 10 achieved at a tuning ratio below 1 stating the best spectral overlap. Around 10 molecules are sensed per HC tip. The investigation results are matching the best-reported SEIRA studies. These findings pave the way toward sensitive, adaptable, and miniaturized IR spectroscopy devices for vital applications like biosensing and environmental monitoring.
表面增强红外吸收（SEIRA）光谱法是一种通过增强分子的振动模式来检测痕量分子甚至蛋白质构象灵活性的有效方法。为了改善光谱特性，我们提出了一种在金属-绝缘体-金属结构中具有蜂窝状（HC）排列的等边铝三角形的表面。通过可调的几何参数，HC纳米天线在红外波段实现了可调谐且宽光谱覆盖。反射率测量结果与数值模拟结果高度吻合。HC结构紧凑且对光偏振不敏感，有利于提高信噪比并增加传感应用所需的热点数量。因此，这些纳米天线适用于通过大等离子体共振与我们的分析物（香草醛）的窄红外振动模式之间的光谱重叠进行精确和宽带的SEIRA传感。与我们之前研究的蝴蝶结纳米天线一致，我们使用HC证明，在调谐比低于1的情况下实现了大于10的SEIRA增强因子，表明具有最佳光谱重叠。每个HC尖端可检测到约10个分子。研究结果与报道的最佳SEIRA研究结果相符。这些发现为用于生物传感和环境监测等重要应用的灵敏、适应性强且小型化的红外光谱设备铺平了道路。
