Dadadzhanov Daler R, Vartanyan Tigran A, Karabchevsky Alina
School of Photonics, Center of Information Optical Technology, ITMO University, 49 Kronverksky pr., St. Petersburg 197101, Russia.
School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
Nanomaterials (Basel). 2020 Jun 29;10(7):1265. doi: 10.3390/nano10071265.
Molecular overtones stretching modes that occupy the near-infrared (NIR) are weak compared to the fundamental vibrations. Here we report on the enhancement of absorption by molecular vibrations overtones via electromagnetic field enhancement of plasmonic nanoparallelepipeds comprising a square lattice. We explore numerically, using finite element method (FEM), gold metasurfaces on a transparent dielectric substrate covered by weakly absorbing analyte supporting N-H and C-H overtone absorption bands around 1.5 μ m and around 1.67 μ m, respectively. We found that the absorption enhancement in N-H overtone transition can be increased up to the factor of 22.5 due to the combination of localized surface plasmon resonance in prolonged nanoparticles and lattice Rayleigh anomaly. Our approach may be extended for sensitive identification of other functional group overtone transitions in the near-infrared spectral range.
与基频振动相比，处于近红外（NIR）区域的分子泛音伸缩模式较弱。在此，我们报告了通过由方形晶格组成的等离子体纳米平行六面体的电磁场增强，分子振动泛音吸收得到增强。我们使用有限元方法（FEM）进行数值研究，研究对象是覆盖有弱吸收分析物的透明介电基板上的金超表面，该分析物分别在1.5μm和1.67μm左右支持N - H和C - H泛音吸收带。我们发现，由于细长纳米颗粒中的局域表面等离子体共振和晶格瑞利异常的结合，N - H泛音跃迁中的吸收增强可提高到22.5倍。我们的方法可扩展用于近红外光谱范围内其他官能团泛音跃迁的灵敏识别。
