表面等离激元金属纳米粒子的多元化结构及应用

目前, 单一的金属纳米粒子结构已经难以满足多学科交叉发展的需求. 因此, 将多种金属纳米粒子(如不同尺寸、 形状、 组分等)集成在同一基底表面, 能够充分发挥不同金属纳米粒子的性质和优势, 极具研究价值和应用价值. 本文介绍了多元化表面等离激元纳米粒子结构的构筑方法, 以及其在信息编码、 光电器件、 能源催化等领域的应用. 最后, 提出了当前在多元化结构制备中存在的挑战, 并展望了利用多元化结构实现性能提升的前景.     

Kinetic Monte Carlo simulations of Au clusters on Si(111)-7 × 7 surface

Self-assembled growth of Au nanoclusters on the Si(111)-7 × 7 surface has been studied using kinetic Monte Carlo simulations. A model considering various atomic processes of deposition, adsorption, diffusion, nucleation, and aggregation is introduced, and the main energetic parameters are optimized based on the experimental results. The evolution of surface morphology during Au growth is simulated in real time, from which the atomic behaviors of Au could be really captured. Most of Au atoms diffuse on the substrate in the very early stage of growth, and Au clusters nucleate and grow with the increasing coverage. The competition among various atomic processes results in the distinct distribution of Au clusters under different coverages. The growth conditions are further optimized, showing that the higher uniformity of Au clusters would be obtained at a low deposition rate and an optimal substrate temperature of about 380 K.     

Design and Synthesis of a Highly Stable Six-hydrogen-bonded Serfassembly Yellowish Green Electroluminescent Molecular Duplex

This paper describes the design, synthesis and characterization of a hydrogen-bonded molecular duplex with 1,8-naphthalimide fluorescent pendants. The two oligoamide molecular strands, with complementary hydrogen bond sequences of DDADAA and AADADD, can form an ultra stable self-assembly duplex. Its molecular structure was confu-med by ^1H NMR and ESI-MS, and its photoluminescence properties were determined. The resulting duplex exhibited a dramatically enhanced photoluminescence （PL） quantum efficiency of 63.7% compared to the corresponding 1,8-naphthalimide segment （32.4%）, suggesting that the formation of the duplex with larger molecular weight could successfully inhibit the quenching of the fluorescent pendant. This novel duplex is a prospective candidate for new electroluminescent emitter.     

Hexacyanoferrate as the Electrochemical Probe for 2-Mercaptobenzothiazole Modified Gold Electrode

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一种新型温度响应性聚氨基酸/聚类肽嵌段共聚物的合成与表征

以正己胺为引发剂, 通过γ-炔丙基-L-谷氨酸羧酸酐(PLG-NCA)和N-正辛基甘氨酸羧酸酐(Oct-NNCA)逐步开环聚合和后修饰策略合成了分子量分布较窄的温度响应性两嵌段共聚物寡聚乙二醇单元修饰的聚(γ-炔丙基-L-谷氨酸)-b-聚(N-正辛基甘氨酸)[(PPLG-g-EG₃)-b-PNOG]. 通过示差扫描量热法(DSC)研究了不同比例聚合物的结晶行为; 利用圆二色谱法(CD)研究了聚合物的二级结构, 并研究了聚合物在水溶液中的自组装行为, 采用透射电子显微镜(TEM)观察了组装后的形貌. 结果表明, 该温度响应性聚合物在室温下呈现α-螺旋结构, 随着温度升高, α-螺旋的构象减少. 该聚合物可以在水溶液中自发组装成棒状结构.     

Design and Synthesis of a Highly Stable Six-hydrogen-bonded Self-assembly Yellowish Green Electroluminescent Molecular Duplex

Since the first fabrication of thin-layer organic electroluminescent(OEL)device in1987by C.W.Tang et al1.,OEL materials had been of ever increasing interest2,3.While up to now,full-color display has been commercialized with small molecules having different structures.In general,host-dopant systems are often employed in RGB OLEDs.This procedure,however,would lead to relatively poor performance for OEL devices,because of the easy aggregation and crystallization of the dopants,which would…     

三聚氰胺与蜜勒胺在Au (111)表面的自组装和氢键识别

Melamine and melem molecules are widely used precursors for synthesizing graphitic carbon nitride (g-C₃N₄), the latter also a hot two-dimensional material with photocatalytic applications. The molecular structures of both are respectively identical to the repeating units of two distinct g-C₃N₄ phases. In this work, the adsorption and self-assembly of melamine and melem on an Au(111) surface were investigated with low-temperature scanning tunneling microscopy (STM). Particularly, the patterns of hydrogen bonds (HBs) in their assemblies were identified and compared. It was found that melamine can only form one type of HB and two kinds of assembly structures, whereas melem can form three types of HBs and six kinds of assembly structures in total. Moreover, the involved HBs can be transformed by tip manipulation. These findings may provide a new strategy for tuning the functionality of surface self-assemblies by manipulating intermolecular hydrogen bonds. This also paves a route for the in situ synthesis of g-C₃N₄ on metallic surfaces and subsequent investigations of their physicochemical properties.     

Intermolecular Interactions in Self-Assembly Process of Sodium Dodecyl Sulfate by Vertically Polarized Raman Spectra

Molecular self-assembly is extremely important in many fields, but the characterization of their corresponding intermolecular interactions is still lacking. The C-H stretching Raman band can reflect the hydrophobic interactions during the self-assembly process of sodium dodecyl sulfate (SDS) in aqueous solutions. However, the Raman spectra in this region are seriously overlapped by the OH stretching band of water. In this work, vertically polarized Raman spectra were used to improve the detection sensitivity of spectra of C-H region for the first time. The spectral results showed that the first critical micelle concentration and the second critical micelle concentration of SDS in water were 8.5 and 69 mmol/L, respectively, which were consistent with the results given by surface tension measurements. Because of the high sensitivity of vertically polarized Raman spectra, the critical micelle concentration of SDS in a relatively high concentration of salt solution could be obtained in our experiment. The two critical concentrations of SDS in 100 mmol/L NaCl solution were recorded to be 1.8 and 16.5 mmol/L, respectively. Through comparing the spectra and surface tension of SDS in water and in NaCl solution, the self-assembly process in bulk phase and at interface were discussed. The interactions among salt ions, SDS and water molecules were also analyzed. These results demonstrated the vertically polarized Raman spectra could be employed to study the self-assembly process of SDS in water.     

十二烷基硫酸钠自组装过程中分子间相互作用力的垂直偏振拉曼光谱研究

Molecular self-assembly is extremely important in many fields, but the characterization of their corresponding intermolecular interactions is still lacking. The C-H stretching Raman band can reflect the hydrophobic interactions during the self-assembly process of sodium dodecyl sulfate (SDS) in aqueous solutions. However, the Raman spectra in this region are seriously overlapped by the OH stretching band of water. In this work, vertically polarized Raman spectra were used to improve the detection sensitivity of spectra of C-H region for the first time. The spectral results showed that the first critical micelle concentration and the second critical micelle concentration of SDS in water were 8.5 and 69 mmol/L, respectively, which were consistent with the results given by surface tension measurements. Because of the high sensitivity of vertically polarized Raman spectra, the critical micelle concentration of SDS in a relatively high concentration of salt solution could be obtained in our experiment. The two critical concentrations of SDS in 100 mmol/L NaCl solution were recorded to be 1.8 and 16.5 mmol/L, respectively. Through comparing the spectra and surface tension of SDS in water and in NaCl solution, the self-assembly process in bulk phase and at interface were discussed. The interactions among salt ions, SDS and water molecules were also analyzed. These results demonstrated the vertically polarized Raman spectra could be employed to study the self-assembly process of SDS in water.