Yin Yanping, Zhu Jin, Wang Zaoji, Ma Guojun, Yuan Huining, Li Xiaolong
College of Electronic and Information, Jiangsu University of Science and Technology, Zhenjiang, China.
Front Chem. 2021 Jan 21;8:553541. doi: 10.3389/fchem.2020.553541. eCollection 2020.
In recent years, the plasma gap resonance maintained by metal-film-coupled nanostructures has attracted extensive attention. This mainly originates from its flexible control of the spectral response and significantly enhanced field strength at the nanoparticle-film junction. In the present study, the tunability of local surface plasmon resonances (LSPRs) of nanorods coupled to a gold film is studied theoretically. To this end, the plasmonic resonances in the nanostructure of individual silver nanorod-gold film (AgNR-film) with different parameters are investigated. Obtained results show that the refractive index sensitivity (S) of nanostructures to the environment increases as the aspect ratio ( ) of nanostructures increase. It is found that when the aspect ratio ( ) is set to 3.5, the figure of merit (FOM) is the highest. Moreover, the variation in the gap distances of the nanorod monomer-gold film, electric field distribution of nanorods dimer, and the corresponding impact on the gold film are studied. It is concluded that the gap size of nanostructures has an exponential correlation with the resonance wavelength. Considering the remarkable influence of the gap size and the surrounding medium environment on the spectral shift of AgNR-film nanostructures, potential applications of the structure as a refractive index sensor and biomolecule measurement are proposed.
近年来，由金属膜耦合纳米结构维持的等离子体间隙共振引起了广泛关注。这主要源于其对光谱响应的灵活控制以及纳米颗粒 - 膜交界处显著增强的场强。在本研究中，从理论上研究了耦合到金膜的纳米棒的局部表面等离子体共振（LSPR）的可调谐性。为此，研究了具有不同参数的单个银纳米棒 - 金膜（AgNR - 膜）纳米结构中的等离子体共振。获得的结果表明，纳米结构对环境的折射率灵敏度（S）随着纳米结构的纵横比（ ）增加而增加。发现当纵横比（ ）设置为3.5时，品质因数（FOM）最高。此外，研究了纳米棒单体 - 金膜的间隙距离变化、纳米棒二聚体的电场分布以及对金膜的相应影响。得出结论，纳米结构的间隙尺寸与共振波长具有指数相关性。考虑到间隙尺寸和周围介质环境对AgNR - 膜纳米结构光谱位移的显著影响，提出了该结构作为折射率传感器和生物分子测量的潜在应用。
