Direct molecular-level near-field plasmon and temperature assessment in a single plasmonic hotspot
Direct molecular-level near-field plasmon and temperature assessment in a single plasmonic hotspot
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在单个等离子体热点中直接的分子水平近场等离子体激元和温度评估
DOI：
10.1038/s41377-020-0260-9
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发表时间：
2020-03-09
影响因子：
19.4
通讯作者：
Deckert, Volker
中科院分区：
文献类型：
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作者：
Richard-Lacroix, Marie;Deckert, Volker
尖端增强拉曼光谱（TERS）目前被广泛认为是探索纳米尺度的必要但仍处于新兴阶段的技术。然而，我们缺乏对关键参数的理解仍然限制了它作为用户友好的分析工具的潜力。尖端的表面等离子体共振、近场温度升高引起的加热和空间分辨率无疑是三个具有挑战性的实验参数。然而，它们也是需要探索的最基本的相关参数，因为它们最终会影响被研究分子的状态，从而影响被探测信号。在这里，我们提出了一种简单而纯粹的实验方法来获取等离子体共振和近场温度的定量信息，这些信息仅由直接产生TERS信号的分子所经历。通过同时探测Stokes和反Stokes光谱强度，使用标准的TERS实验设备评估了分子水平和时间函数的详细近场光学响应。以自组装的16-巯基十六烷酸单层共价键合在超平金表面作为验证物。光谱中闪烁线的观察也为实验过程中尖端的横向分辨率和原子尺度热诱导形态变化提供了重要信息。这项研究提供了前所未有的关于物理参数的分子水平信息，这些参数在TERS条件下对实验产生了至关重要的影响。因此，本研究提高了测试系统在日常操作中的可用性。获得的信息对于任何实验等离子体研究和在纳米尺度测温领域的应用都是至关重要的。尖端增强拉曼光谱：利用尖端增强拉曼光谱（TERS）进行方便的表征实验，可以方便地定量表征过程，从而有助于优化过程。TERS是一种高灵敏度的技术，它结合了拉曼光谱的化学特异性和尖端原子力显微镜的空间分辨率。然而，评估和量化技术背后潜在的等离子体机制是具有挑战性的。现在，来自德国耶拿的Marie Richard-Lacroix和Volker Deckert报告说，同时收集和分析Stokes和反Stokes拉曼信号提供了关于基于等离子体激元的TERS热点的关键信息，包括等离子体激元共振的精确光谱位置和宽度以及近场温度。在金底物上用巯基十二烷酸单层进行的透射电镜实验证实了该方法的可行性。
Tip-enhanced Raman spectroscopy (TERS) is currently widely recognized as an essential but still emergent technique for exploring the nanoscale. However, our lack of comprehension of crucial parameters still limits its potential as a user-friendly analytical tool. The tip's surface plasmon resonance, heating due to near-field temperature rise, and spatial resolution are undoubtedly three challenging experimental parameters to unravel. However, they are also the most fundamentally relevant parameters to explore, because they ultimately influence the state of the investigated molecule and consequently the probed signal. Here we propose a straightforward and purely experimental method to access quantitative information of the plasmon resonance and near-field temperature experienced exclusively by the molecules directly contributing to the TERS signal. The detailed near-field optical response, both at the molecular level and as a function of time, is evaluated using standard TERS experimental equipment by simultaneously probing the Stokes and anti-Stokes spectral intensities. Self-assembled 16-mercaptohexadodecanoic acid monolayers covalently bond to an ultra-flat gold surface were used as a demonstrator. Observation of blinking lines in the spectra also provides crucial information on the lateral resolution and indication of atomic-scale thermally induced morphological changes of the tip during the experiment. This study provides access to unprecedented molecular-level information on physical parameters that crucially affect experiments under TERS conditions. The study thereby improves the usability of TERS in day-to-day operation. The obtained information is of central importance for any experimental plasmonic investigation and for the application of TERS in the field of nanoscale thermometry.Tip-enhanced Raman spectroscopy: convenient characterization Experiments involving tip-enhanced Raman spectroscopy (TERS) could benefit from a convenient method to quantitatively characterize the process and thus aid its optimization. TERS is a highly sensitive technique that combines the chemical specificity of Raman spectroscopy with the spatial resolution of tip-based atomic force microscopy. However, evaluating and quantifying the underlying plasmon mechanisms behind the technique is challenging. Now, Marie Richard-Lacroix and Volker Deckert from Jena, Germany, report that simultaneous collection and analysis of Stokes and anti-Stokes Raman signals provide critical information about the plasmon-based TERS hotspot, including the precise spectral position and width of the plasmon resonance and the near-field temperature. TERS experiments performed with a monolayer of mercaptododecanoic acid on a gold substrate confirm the viability of the approach.