Probing the Mechanisms of Strong Fluorescence Enhancement in Plasmonic Nanogaps with Sub-nanometer Precision
Probing the Mechanisms of Strong Fluorescence Enhancement in Plasmonic Nanogaps with Sub-nanometer Precision
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DOI：
10.1021/acsnano.0c01973
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发表时间：
2020-11-24
期刊：
影响因子：
17.1
通讯作者：
Wu, Wei
中科院分区：
文献类型：
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作者：
Song, Boxiang;Jiang, Zhihao;Wu, Wei
由于强烈的局部场增强，在金属表面附近显示出等离激元增强荧光。同时，当荧光团分子和相邻金属之间的间距减小到几纳米的阈值以下时，观察到荧光猝灭。在这里，我们介绍了一项技术，将荧光团分子放置在成对的可折叠纳米指之间的等离子体热点中，间隙尺寸可在亚纳米精度下调节。对于不同的介电间隔材料，通过实验确定了具有最大等离子体增强荧光的最佳间隙尺寸。超强的局部场增强能够同时检测和表征荧光光谱中清晰的拉曼指纹。因此，该平台能够对竞争激发增强和发射猝灭过程进行原位监测。我们系统地研究了荧光猝灭背后的机制。开发了一个量子力学模型，它解释了实验数据，并将指导等离子体增强光谱应用的未来设计。
Plasmon-enhanced fluorescence is demonstrated in the vicinity of metal surfaces due to strong local field enhancement. Meanwhile, fluorescence quenching is observed as the spacing between fluorophore molecules and the adjacent metal is reduced below a threshold of a few nanometers. Here, we introduce a technology, placing the fluorophore molecules in plasmonic hotspots between pairs of collapsible nanofingers with tunable gap sizes at sub-nanometer precision. Optimal gap sizes with maximum plasmon enhanced fluorescence are experimentally identified for different dielectric spacer materials. The ultrastrong local field enhancement enables simultaneous detection and characterization of sharp Raman finger-prints in the fluorescence spectra. This platform thus enables in situ monitoring of competing excitation enhancement and emission quenching processes. We systematically investigate the mechanisms behind fluorescence quenching. A quantum mechanical model is developed which explains the experimental data and will guide the future design of plasmon enhanced spectroscopy applications.