Plasmonic photoluminescence for recovering native chemical information from surface-enhanced Raman scattering

表面增强拉曼光谱(SERS)可以提供高达单分子的检测灵敏度和特异的分子指纹信息，是一个非常有前景的分析技术。SERS增强主要源自贵金属纳米结构的局域表面等离激元共振(LSPR)效应。虽然SERS研究者早已意识到该效应强烈依赖于激光波长，并对不同频率的拉曼谱峰增强效果不同，但是迄今为止仍缺乏有效的方法对SERS谱峰相对强度进行可靠的矫正，也常有文献错误解读SERS强度信息，从而过度或错误地解释实验结果。 在该工作中，任斌教授课题组采用单粒子光谱技术从实验上直接检测SERS光谱和金属纳米粒子的光致发光谱(PL)，通过定量研究两者的关联，提出了一种普适的方法矫正LSPR对不同拉曼谱峰相对强度的影响，为理解表面物种构型和作用方式提供了本征的化学指纹信息。【Abstract】Surface-enhanced Raman scattering (SERS) spectroscopy has attracted tremendous interests as a highly sensitive label-free tool. The local field produced by the excitation of localized surface plasmon resonances (LSPRs) dominates the overall enhancement of SERS. Such an electromagnetic enhancement is unfortunately accompanied by a strong modification in the relative intensity of the original Raman spectra, which highly distorts spectral features providing chemical information. Here we propose a robust method to retrieve the fingerprint of intrinsic chemical information from the SERS spectra. The method is established based on the finding that the SERS background originates from the LSPR-modulated photoluminescence, which contains the local field information shared also by SERS. We validate this concept of retrieval of intrinsic fingerprint information in well controlled single metallic nanoantennas of varying aspect ratios. We further demonstrate its unambiguity and generality in more complicated systems of tip-enhanced Raman spectroscopy (TERS) and SERS of silver nanoaggregates.该工作得到国家自然科学基金委（项目批准号：21633005、21621091和J1310024）、科技部（项目批准号：2013CB933703、2016YFA0200601）、教育部等部门的大力资助与支持

Probing the edge-related properties of atomically thin MoS2 at nanoscale

层状二维材料具有独特的物理化学性质，使其在光电器件、传感、能源和催化等领域得到了高度关注和广泛应用。二维材料在制备过程中不可避免引入结构缺陷，虽然这些缺陷尺度仅为数纳米甚至单原子，但是会极大地改变材料的结构和电子性质，从而影响其应用。化学化工学院任斌教授课题组在层状二维材料缺陷表征方面取得进展。该工作表明了TERS在原位、高空间分辨表征缺陷位的结构和电子性质方面具有独特的优势，可以进一步推广到其他二维材料，从而有效地指导缺陷设计和材料应用。 该工作通过校内外课题组紧密合作，在任斌教授、谭平恒研究员（中科院半导体研究所）和王翔博士共同指导下完成。实验部分主要由黄腾翔博士（第一作者，已毕业化学系博士生）完成，电子能带结构与光谱理论计算由谭平恒研究员课题组从鑫博士生（共同第一作者）完成，吴思思、林楷强、姚旭、何玉韩、吴江滨、包一凡、黄声超等参与了实验与讨论。【Abstract】Defects can induce drastic changes of the electronic properties of two-dimensional transition metal dichalcogenides and influence their applications. It is still a great challenge to characterize small defects and correlate their structures with properties. Here, we show that tipenhanced Raman spectroscopy (TERS) can obtain distinctly different Raman features of edge defects in atomically thin MoS2, which allows us to probe their unique electronic properties and identify defect types (e.g., armchair and zigzag edges) in ambient. We observed an edgeinduced Raman peak (396 cm−1) activated by the double resonance Raman scattering (DRRS) process and revealed electron–phonon interaction in edges. We further visualize the edge-induced band bending region by using this DRRS peak and electronic transition region using the electron density-sensitive Raman peak at 406 cm−1. The power of TERS demonstrated in MoS2 can also be extended to other 2D materials, which may guide the defect engineering for desired properties.The authors acknowledge the final supports from MOST of China (2016YFA0200601 and 2016YFA0301204), NSFC (21633005, 21790354, 21503181, 21711530704, 21621091, 11874350, 11474277, and 11434010), Natural Science Foundation of Fujian Province (2016J05046), and China Postdoctoral Science Foundation (2017M622062). 研究工作得到科技部、国家自然科学基金委员会、福建省自然科学基金和中国博士后基金资助

部分耗尽型注氟SIMOX器件的电离辐射效应

采用在SIMOX圆片埋氧层中注入氟(F)离子的方法改善SIMOX的抗总剂量辐射能力,通过比较未注F样品和注F样品辐照前后SIMOX器件Ids-Vgs特性和阈值电压,发现F具有抑制辐射感生pMOSFET和nMOSFET阈值电压漂移的能力,并且可以减小nMOSFET中由辐照所产生的漏电流.说明在SOI材料中前后Si/SiO2界面处的F可以减少空穴陷阱密度,有助于提高SIMOX的抗总剂量辐射能力