Zheng Chunjie, Jia Tianqing, Zhao Hua, Xia Yingjie, Zhang Shian, Feng Donghai, Sun Zhenrong
State Key Laboratory of Precision Spectroscopy, East China Normal University Shanghai 200062 P. R. China
RSC Adv. 2018 Jan 19;8(7):3381-3391. doi: 10.1039/c7ra12666b. eCollection 2018 Jan 16.
This paper reports a narrow Fano resonance of 3D nanocrescent and its application in the label-free detection of single molecules. The Fano resonance depends not only on the gap size but also on the height. The Fano resonance originates from the interference between the quadrupolar mode supported by the horizontal crescent and the dipolar mode along the nanotip. When the height of 3D nanocrescent is 30 nm, the width of Fano resonance is as narrow as 10 nm. The narrow linewidth is caused by the strong narrow resonant absorption coming from the dipolar mode of nanotip overlapping with the quadrupolar mode of nanocrescent, where the absorption spectra are calculated under a horizontal incident light. The narrow Fano resonance is highly sensitive to a single nanoparticle trapped by the nanocrescent. The wavelength shift increases linearly with the refractive index with the relation of Δ = 22.10 - 28.80, and increases with the size of trapped nanoparticle following a relation of Δ = 0.826 × . These results indicate that if a protein nanoparticle with radius of 2.5 nm is trapped by the nanocrescent, the shift is as large as 4.03 nm.
本文报道了三维纳米新月形结构的窄Fano共振及其在单分子无标记检测中的应用。Fano共振不仅取决于间隙尺寸，还取决于高度。Fano共振源于水平新月形结构所支持的四极模式与沿纳米尖端的偶极模式之间的干涉。当三维纳米新月形结构的高度为30纳米时，Fano共振的宽度窄至10纳米。窄线宽是由纳米尖端的偶极模式与纳米新月形结构的四极模式重叠产生的强烈窄共振吸收引起的，其中吸收光谱是在水平入射光下计算的。窄Fano共振对被纳米新月形结构捕获的单个纳米颗粒高度敏感。波长 shift随折射率呈线性增加，关系为Δ = 22.10 - 28.80，并且随捕获纳米颗粒的尺寸增加，遵循关系Δ = 0.826 × 。这些结果表明，如果半径为2.5纳米的蛋白质纳米颗粒被纳米新月形结构捕获，shift高达4.03纳米。 （注：原文中“Δ = 0.826 × ”后面似乎缺少了具体内容）
