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标题：Cascaded nanooptics to probe microsecond atomic-scale phenomena
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作者：Marlous Kamp ; Bart de Nijs ; Nuttawut Kongsuwan 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：26
页码：14819-14826
DOI：10.1073/pnas.1920091117
出版社：The National Academy of Sciences of the United States of America
摘要：Plasmonic nanostructures can focus light far below the diffraction limit, and the nearly thousandfold field enhancements obtained routinely enable few- and single-molecule detection. However, for processes happening on the molecular scale to be tracked with any relevant time resolution, the emission strengths need to be well beyond what current plasmonic devices provide. Here, we develop hybrid nanostructures incorporating both refractive and plasmonic optics, by creating SiO 2 nanospheres fused to plasmonic nanojunctions. Drastic improvements in Raman efficiencies are consistently achieved, with (single-wavelength) emissions reaching 10 7 counts⋅mW −1 ⋅s −1 and 5 × 10 5 counts∙mW −1 ∙s −1 ∙molecule −1 , for enhancement factors >10 11 . We demonstrate that such high efficiencies indeed enable tracking of single gold atoms and molecules with 17-µs time resolution, more than a thousandfold improvement over conventional high-performance plasmonic devices. Moreover, the obtained (integrated) megahertz count rates rival (even exceed) those of luminescent sources such as single-dye molecules and quantum dots, without bleaching or blinking.
关键词：nanophotonics ; nanolensing ; surface-enhanced Raman scattering (SERS) ; few-molecule sensing ; microsecond integration times