Giordano M C, Tzschoppe M, Barelli M, Vogt J, Huck C, Canepa F, Pucci A, Buatier de Mongeot F
Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
Kirchhoff Institute for Physics, University of Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
ACS Appl Mater Interfaces. 2020 Mar 4;12(9):11155-11162. doi: 10.1021/acsami.9b19719. Epub 2020 Feb 25.
Capabilities of highly sensitive surface-enhanced infrared absorption (SEIRA) spectroscopy are demonstrated by exploiting large-area templates (cm) based on self-organized (SO) nanorod antennas. We engineered highly dense arrays of gold nanorod antennas featuring polarization-sensitive localized plasmon resonances, tunable over a broadband near- and mid-infrared (IR) spectrum, in overlap with the so-called "functional group" window. We demonstrate polarization-sensitive SEIRA activity, homogeneous over macroscopic areas and stable in time, by exploiting prototype self-assembled monolayers of IR-active octadecanthiol (ODT) molecules. The strong coupling between the plasmonic excitation and molecular stretching modes gives rise to characteristic Fano resonances in SEIRA. The SO engineering of the active hotspots in the arrays allows us to achieve signal amplitude improved up to 5.7%. This figure is competitive to the response of lithographic nanoantennas and is stable when the optical excitation spot varies from the micro- to macroscale, thus enabling highly sensitive SEIRA spectroscopy with cost-effective nanosensor devices.
通过利用基于自组织（SO）纳米棒天线的大面积（厘米级）模板，展示了高灵敏度表面增强红外吸收（SEIRA）光谱的能力。我们设计了高密度的金纳米棒天线阵列，其具有偏振敏感的局域等离子体共振，可在宽带近红外和中红外（IR）光谱范围内调谐，与所谓的“官能团”窗口重叠。通过利用具有红外活性的十八烷硫醇（ODT）分子的原型自组装单分子层，我们展示了在宏观区域上均匀且随时间稳定的偏振敏感SEIRA活性。等离子体激发与分子拉伸模式之间的强耦合在SEIRA中产生了特征性的法诺共振。对阵列中活性热点的SO工程使我们能够将信号幅度提高到5.7%。该数值与光刻纳米天线的响应具有竞争力，并且当光激发光斑从微观尺度变化到宏观尺度时保持稳定，从而能够使用具有成本效益的纳米传感器设备实现高灵敏度SEIRA光谱。
