Surface Enhanced Visible Absorption of Dye Molecules in the Near-Field of Gold Nanoparticles
Surface Enhanced Visible Absorption of Dye Molecules in the Near-Field of Gold Nanoparticles
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DOI：
10.1038/s41598-020-60839-0
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发表时间：
2020-03-03
影响因子：
4.6
通讯作者：
Sekkat, Z.
中科院分区：
文献类型：
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作者：
Elhani, S.;Ishitobi, H.;Sekkat, Z.
表面增强吸收是由表面增强荧光和拉曼散射引起的等离子体效应，它被清楚地报道发生在光谱的红外区域。在本文中，我们明确地表明，它也发生在光谱的可见区域使用染料；例如，偶氮染料在该区域表现出良好的光吸收，而金纳米颗粒则作为等离子体纳米天线，当偶氮染料和纳米颗粒被掺入聚合物的固体薄膜中时，它们可以捕获并重新辐射光。在这种结构中，可以使用比纳米颗粒大得多的染料浓度和比表面增强效应研究中使用的分子薄层的吸收路径长度大得多的吸收路径。此外，染料还会发生形状和取向的变化；即偏振光吸收后的异构化和重定向；通过两个单独的实验观察了表面增强的可见光吸收；即紫外-可见吸收光谱和光致双折射，因为从这两个实验中检测到的信号与染料的消光系数成正比。纳米颗粒的存在增强了染料的吸收和光取向。
Surface enhanced absorption is a plasmonic effect parenting to surface enhanced fluorescence and Raman scattering, and it was clearly reported to occur in the infrared region of the spectrum of light. In this paper, we unambiguously show that it also occurs in the visible region of the spectrum by using a dye; i.e. an azo-dye, which exhibits a good light absorption in that region, and gold nanoparticles, which act as plasmonic nanoantennas that capture and re-radiate light, when the azo-dyes and the nanoparticles are incorporated in the bulk of solid films of polymer. In such a configuration, it is possible to use a dye concentration much larger than that of the nanoparticles and absorption path lengths much larger than those of the molecularly thin layers used in surface enhanced effects studies. In addition, the dye undergoes shape and orientation change; i.e. isomerization and reorientation, upon polarized light absorption; and the observation of surface enhanced visible absorption is done by two separate experiments; i.e. UV-visible absorption spectroscopy and photo-induced birefringence, since the signals detected from both experiments are directly proportional to the extinction coefficient of the dye. Both the dye's absorption and photoorientation are enhanced by the presence of the nanoparticles.