Probing nanoscale spatial distribution of plasmonically excited hot carriers

表面等离激元（SP）效应可产生远高于热平衡下费米能级能量的热电子-空穴对（热载流子），从而能够引发和促进相关的光电或者化学过程，为在纳米尺度上高效利用光能实现物质和能量转化提供了极为有效的手段，化学化工学院任斌教授课题组利用前期自主发展的电化学针尖增强拉曼光谱技术，通过调控电位开关SP热载流子催化的反应，实现了有效热载流子催化反应区域的纳米分辨成像，使反应区域在实空间的分布可视化。实验上获得了有效热载流子的输运距离，从而证明了能量越高的热载流子越需要在更短的输运距离范围内收集捕获。 该工作在任斌教授和王翔副教授的共同指导下完成。实验主要由化学化工学院已毕业博士生黄声超完成。理论计算主要由电子科学与技术学院的朱锦峰副教授和已毕业硕士生李察微完成。此外，化学化工学院已毕业硕士生赵庆庆、博后何玉韩和胡树等人也参与了部分研究与课题讨论。【Abstract】Surface plasmons (SPs) of metals enable the tight focusing and strong absorption of light to realize an efficient utilization of photons at nanoscale. In particular, the SP-generated hot carriers have emerged as a promising way to efficiently drive photochemical and photoelectric processes under moderate conditions. In situ measuring of the transport process and spatial distribution of hot carriers in real space is crucial to efficiently capture the hot carriers.Here, we use electrochemical tip-enhanced Raman spectroscopy (EC-TERS) to in situmonitor an SP-driven decarboxylation and resolve the spatial distribution of hot carriers with a nanometer spatial resolution. The transport distance of about 20 nm for the reactive hot carriers is obtained from the TERS imaging result. The hot carriers with a higher energy have a shorter transport distance. These conclusions can be guides for the design and arrangement of reactants and devices to efficiently make use of plasmonic hot carriers.The authors acknowledge the financial supports from MOST of China (2016YFA0200601), NSFC (21633005, 21790354, 21503181, 21711530704, U1830116), Natural Science Foundation of Fujian Province (2016J05046), China Postdoctoral Science Foundation (2017M622062) and the Fundamental Research Funds for the Central Universities (20720190010).本研究工作得到了国家自然科学基金委和科技部等的资助和支持

Domestic violence treatment response and recidivism: A review and implications for the study of family violence

Although domestic violence is a significant societal problem, which continues to receive public and private sector attention, intervention and treatment programs have proven inconsistent in their success. This paper reviews the published literature on domestic violence treatment efficacy and post-treatment recidivism and explores the related factors. In addition, challenges in the assessment of domestic violence are briefly discussed. Finally, recent developments are discussed along with their potential benefits, and an appeal is made for the need to study domestic violence in the broader context of family violence

A Collaborative filtering system for an on-line newspaper

Many online newspapers provide news without consideration for reader's tastes. Collaborative filtering solves this problem by recommending articles based upon ratings by others. Collaborative filtering can be enhanced by content-based filtering when ratings are sparse. We applied a blend of collaborative and content-based filtering to an online newspaper, the Worcester Telegram and Gazette. Our system consists of a web-based interface, a back-end recommendation engine, and a database. We analyze results of the project and propose direction for future work

Recent Progress in the Mechanistic Understanding of CO2 Reduction on Copper

本文从历史角度综述了二氧化碳在铜基催化剂上的还原机理的最新研究进展，对区分C1和C2产物路径发生的机制，以及调控二氧化碳还原产物选择性的影响因素和方法进行了重点阐述，着重讨论了如何利用电化学红外光谱与微分电化学质谱等技术在揭示反应机理方面的研究思路与方法学.In this review, we present the major developments in the understanding of the mechanisms of the electrochemical reduction of CO2 from a historical perspective. Most of the work discussed in this review was carried out at copper electrodes, as this is the only material at which hydrocarbons are produced in reasonable quantities. The emphasis focuses on the differentiation of mechanisms for the generation of C1 and C2 products as well as factors and methods for controlling the product selectivity of CO2 reduction. We have highlighted ambiguities, assumptions, and important methodologies, such as differential electrochemical mass spectrometry and electrochemical in-situ infrared spectroscopy, which help greatly to clarify these issues in the literature.This work was supported by the Natural Science Foundation of China(No. 91545124, No. 21750110437). MMS is supported by the Chinese Academy of Sciences President’s International Fellowship Initiative (Grant No. 2017PM0049)作者联系地址：合肥微尺度物质科学国家研究中心，中国科技大学化学物理系，安徽 合肥 230026Author's Address: Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, China通讯作者E-mail：[email protected]

Electron Transfer-Induced Blinking in Ag Nanodot Fluorescence

Various single-standed DNA-encapsulated Ag nanoclusters (nanodots) exhibit strong, discrete fluorescence with solvent polarity-dependent absorption and emission throughout the visible and near-IR. All species examined, regardless of their excitation and emission energies, show similar µs single-molecule blinking dynamics and near IR transient absorptions. The polarity dependence, µsec blinking, and indistinguishable µsec-decaying transient absorption spectra for multiple nanodots suggest a common charge transfer-based mechanism that gives rise to nanodot fluorescence intermittency. Photoinduced charge transfer that is common to all nanodot emitters is proposed to occur from the Ag cluster into the nearby DNA bases to yield a long-lived charge-separated trap state that results in blinking on the single molecule level

Preparation of Highly Fluorescent Host–Guest Complexes with Tunable Color upon Encapsulation

Unlike previous coordinative host–guest systems, highly emissive host–guest complexes (up to Φ_F = 0.5) were successfully prepared upon encapsulation of various fluorescent dyes (e.g., BODIPY and coumarin derivatives) by a Pt­(II)-linked coordination capsule in water. Picosecond time-resolved spectroscopy elucidates the photophysical behaviors of the obtained complexes. Notably, the emission color of the fluorescent guest within the capsule can be readily modulated upon pairwise encapsulation with planar aromatic molecules

Probing nanoscale spatial distribution of plasmonically excited hot carriers

Revealing the spatial distribution of hot carriers in real space is crucial to their efficient utilization. Here, the authors show that in-situ electrochemical tip-enhanced Raman spectroscopy is able to resolve the spatial distribution of reactive hot carriers with a nanometer spatial resolution

Nonlinear Optical Pulse Suppression via Ultrafast Photoinduced Electron Transfer in an Aggregated Perylene Diimide/Oligothiophene Molecular Triad

A donor–acceptor–donor triad material in which two quinquethiophene moieties are attached via nonconjugated, flexible bridges to the 1,7-positions (80% isomer) and 1,6-positions (20% isomer) of a perylene diimide (<b>PDI-5T</b>) has been synthesized, and its nonlinear suppression of nanosecond laser pulses in the 680–750 nm range has been studied. The kinetics of the photoinduced charge separation processes have been characterized using femtosecond transient pump–probe spectroscopy. Excitation of either the quinquethiophene donor or perylene diimide acceptor leads to ultrafast (<700 fs) photoinduced charge separation, yielding quinquethiophene and perylene diimide radical ions that are strongly absorbing in the red–near-IR region. Despite the short lifetime (52 ps) of the charge-separated state, reasonably strong nonlinear suppression of nanosecond pulses, with figures-of-merit up to 14, has been realized with 4 mM solutions of <b>PDI-5T</b>. Although the radical ion absorption (RIA) is much stronger at 750 nm than that at 680 or 700 nm, the best optical suppression figures-of-merit were observed at 680 and 700 nm. Comparison of the optical parameters at these wavelengths suggests that the stronger ground-state absorption, due to aggregates of <b>PDI-5T</b>, is responsible for the enhanced figure-of-merit at the shorter wavelength