化学还原法制备金纳米棒及其光学性质研究

在十六烷基三甲基溴化铵和十四烷基二甲基苄基氯化铵形成的双分子层胶体溶液中，利用种子生长的方法，控制硝酸银添加物制备纵横比不同金纳米棒．在表面活性剂作用下，金种沿着[100]方向生长，其它方向受限生长，形成各向异性的纳米结构．根据实验结果，利用时域有限差分方法模拟金纳米棒的生长，选择折射率为1．33，探索金纳米棒光学吸收谱，较好符合了实验结果．     

Growth and optical absorption properties of silver nanorod arrays in porous anodic aluminum oxide templates

Silver nanorod arrays have been fabricated by alternat-ing current(AC) and pulsed direct current(DC) electrodeposition in porous anodic aluminum oxide(AAO) templates with controlled pore diameters of 19,38,and 65 nm,respectively.The variation of their optical absorption properties with the incident angle and the nanorods length(corresponding to the electrodeposition time) has been investigated.Optical absorption spectra show that the posi-tion of longitudinal surface plasmon resonance(LSPR) peak has a small blueshift with the increase of incident angle of the excitation light.While the aspect ratio of the nanorods increases,the position of LSPR peak first redshifts and then blueshifts to a certain wave-length.Furthermore,the position of LSPR peak can be tuned,ranging from 550 nm to 900 nm,which makes it possible to cou-ple various wavelength of excitation source to assist radiative en-ergy transfer to the acceptor.     

ZnS/PVA纳米复合薄膜的制备及其非线性三光子吸收研究

采用原位复合的方法制备出厚度为20μm的聚乙烯醇(PVA)与ZnS纳米微粒复合的薄膜,利用透射电镜(TEM)和X射线衍射(XRD)研究薄膜样品的微结构性能,证明已制备出立方晶相的针状ZnS纳米晶.用Z-扫描技术研究ZnS/PVA纳米复合薄膜的非线性光学性质,发现该薄膜对532 nm纳秒脉冲激光表现出较强的非线性吸收效应,而且非线性吸收强度随入射光强的增加而减少.该非线性吸收主要由纳米ZnS的三光子吸收引起,并伴随弱饱和吸收现象发生.     

Synthesis and Largely Enhanced Nonlinear Refraction of Au@Cu_2O Core-Shell Nanorods

Au@Cu_2O core-shell nanorods with tunable thickness of Cu_2O shell were synthesized and their linear and nonlinear optical responses were investigated. Two transverse plasmon resonance peaks were observed when the Au nanorods were coated with Cu_2O shells, which were adjusted by the Cu_2O shell thickness. The nonlinear absorption of the Au@Cu_2O nanorods is enhanced by 5 times at the longitudinal plasmon resonance wavelength compared with that of bare Au nanorods. More intriguingly, largely enhanced nonlinear refraction and suppressed nonlinear absorption at the transverse plasmon resonance wavelength were observed in the Au@Cu_2O nanorods. Our findings indicate the existence of strong local field enhancement at the interface between the Au core and the Cu_2O shell, which would provide a promising strategy in designing plasmonic nonlinear nanodevices with good nonlinear figures of merit.     

多臂CdS纳米棒的合成、表征及修饰

以二乙基二硫代氨基甲酸镉为单一前驱体,在油胺介质中裂解,得到多臂状CdS纳米棒.研究了前体中Cd/S配比和裂解时间对CdS纳米棒光学性能的影响.实验结果表明,该方法合成的CdS纳米棒为六方晶态结构,直径约为5 nm,臂长为36 nm左右,其耐光漂白性好,在最佳条件下量子产率可达2O%.分别用透射电镜、高分辨透射电镜、紫外-可见吸收光谱、荧光光谱对样品的结构形态和光学特性进行了表征.同时,采用二巯基辛酸为修饰剂,得到了性能优良的水溶性CdS纳米棒.     

FeWO_4 nanorods with excellent UV–Visible light photocatalysis

FeWO_4 nanorods were synthesized through a hydrothermal progress with the assistant of L-cysteine. The synthesized FeWO_4 nanorods were characterized by X-ray powder diffraction, Raman spectrometer, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy,energy-dispersive X-ray spectroscope and X-ray photoelectron spectroscopy. The optical property, photocatalytic activity and magnetic property of the synthesized FeWO_4 nanorods were investigated. The photodecomposition of Methyl orange for FeWO_4 nanorods depends on the wavelength of the irradiating light. Under ultraviolet-visible light irradiation, FeWO_4 nanorods show higher photocatalytic activity for the decomposition of Methyl orange than that of ultraviolet light irradiation. A possible mechanism of FeWO_4 on the decomposition of Methyl orange was proposed. The value of Néel temperature is lower than that of bulk FeWO_4, which is associated with the size effects and the shape of the synthesized FeWO_4 nanorods.     

Synthesis and Largely Enhanced Nonlinear Refraction of Au@Cu<Subscript>2</Subscript>O Core-Shell Nanorods

Au@Cu₂O core-shell nanorods with tunable thickness of Cu₂O shell were synthesized and their linear and nonlinear optical responses were investigated. Two transverse plasmon resonance peaks were observed when the Au nanorods were coated with Cu₂O shells, which were adjusted by the Cu₂O shell thickness. The nonlinear absorption of the Au@Cu₂O nanorods is enhanced by 5 times at the longitudinal plasmon resonance wavelength compared with that of bare Au nanorods. More intriguingly, largely enhanced nonlinear refraction and suppressed nonlinear absorption at the transverse plasmon resonance wavelength were observed in the Au@Cu₂O nanorods. Our findings indicate the existence of strong local field enhancement at the interface between the Au core and the Cu₂O shell, which would provide a promising strategy in designing plasmonic nonlinear nanodevices with good nonlinear figures of merit.     

理论模拟氧化锌纳米棒的表面复合速率

表面复合是严重影响纳米结构半导体发光性质及器件性能的重要因素之一.氧化锌(ZnO)因其具有优异的光电性质和物化稳定性在太阳能电池和发光二极管等光电器件领域展现出巨大的应用前景.本文利用MATLAB程序求解扩散方程,对化学水浴沉积法合成的ZnO纳米棒的表面复合速率进行理论模拟计算.与实验结果相结合,揭示表面复合对ZnO纳米棒发光性质的影响.     

ZnO纳米棒的结构及其光学性质研究

应用水热方法,合成了直径约30nm的ZnO纳米棒并通过X射线衍射、透射电子显微镜和拉曼光谱对其结构进行表征.还研究了他们的光学性质,如:室温下的光致发光谱以及温度依赖的光致发光光谱.研究结果显示,反应溶液的pH值修饰了ZnO纳米棒的长径比.观测到了ZnO纳米棒中源自激子的紫外发光(3.2eV)和来自于深能级缺陷的可见发光(2.0eV).根据变温发射光谱,通过对实验数据的拟合获得了一些重要的参数,如:激子的爱因斯坦温度及深能级的热激活能等.     

Magnetically separable and visible light-active Ag/NiCo_2O_4 nanorods prepared by a simple route for superior photodegradation of atrazine in water

Atrazine(ATZ) is a known herbicide used in agriculture and caused many concerns according to its toxicity.Herein,we have prepared NiCo_2 O_4 nanorods that can work as a photocatalyst under visible light exposure by Ag loading through a simple route.The characterizations revealed the role of Ag for improving the structural,optical and optoelectronic properties of the produced photocatalyst.The Ag loading with 5 wt% confirms the minimization of the bandgap from 3.6 down to 2.57 eV with enhanced visible light absorption and sustaining the magnetic properties.The Ag/NiCo_2 O_4 nanorods showed a superior photodegradation of ATZ within 20 min at2.0 g L~(-1) with excellent recyclability.The enhancement of the photocatalytic activity is referred to the local surface plasmon resonance of Ag-loaded photocatalyst.This reduces the electron-hole recombination and outperforms the unloaded sample.This work is highlighting the application of magnetically separable spinel photocatalysts for the removal of herbicides and water remediation.     

Minimizing the effect of near-distance dielectric sensitivity on retrieving average aspect ratio of gold nanorod by optical extinction spectroscopy: in the case of CTAB adsorption

The aspect ratio （AR） is one of the most intriguing parameters of gold nanorods （GNRs）, which plays an important role in determining localized surface plasmon （LSPR） properties. Instead of conventional imaging techniques, the optical extinction spectroscopy （OES） method has been developed for allowing fast sta-tistically measuring the average AR under static approxi- mation. In this work, combining with the previous achievements in spectroscopic technique, we further ana-lyze the effects of gold dielectric function and near dis-tance dielectric sensitivity. The former may reflect possible dielectric loss of real Au samples from ideal single crys- talline. The latter reflects the cetyltrimethylammonium bromide （CTAB） adsorption on the surface of GNR indu- ces different LSPR shifts below and above critical micelle concentration （CMC）. However, their effect on the deter-mination of AR has not been evaluated in OES method. The average AR measurements as a function of absorbance of CTAB-GNRs and LSPR maximum below the CMC were studied. Our results indicate that after considering these factors, the mean ARs obtained from spectroscopic techniques are closer to those obtained from imaging techniques.     

基于第一性原理计算Stone-Wales石墨烯的光学性质

采用基于密度泛函理论的第一性原理计算研究了一种新型二维材料Stone-Wales(SW)石墨烯的光学性质。基于介电函数，反射谱和吸收谱等参数对其进行研究。结果显示这种狄拉克碳材料的光学性质在不同极化光下都表现出强各向异性。介电函数实部表明其静态介电常数大，这说明该材料具有很多可利用的自由载流子，所以具有优良的导电性，可作为新一代纳米电子器件的候选材料。此外，吸收光谱和反射光谱表明了SW石墨烯在全光谱区内具有比较敏感的光谱响应，这说明该材料在光电子器件领域非常具有应用前景。     

运用有效介质理论研究Au/AAO纳米复合结构的光学特性

运用Maxwell-Garnett(M-G)有效介质理论模拟了Au/阳极氧化铝(AAO)纳米有序阵列复合结构在200~2 500 nm波段内的光学常数,并研究了300~1 000 nm波段Au组分的体积分数及长径比对Au/AAO复合结构的光学常数n和k的影响.结果表明,Au组分的体积分数和长径比对Au/AAO复合结构的光学常数有较强的调制作用.同时发现,Au组分体积分数对Au/AAO复合结构吸收、反射特性有较大影响.     

Structural,morphological, and optical properties of tin(Ⅳ) oxide nanoparticles synthesized using Camellia sinensis extract: a green approach

Tin oxide (SnO2) nanoparticles were cost-effectively synthesized using nontoxic chemicals and green tea (Camellia sinensis) extract via a green synthesis method.The structural properties of the obtained nanoparticles were studied using X-ray diffraction,which indicated that the crystallite size was less than 20 nm.The particle size and morphology of the nanoparticles were analyzed using scanning electron microscopy and transmission electron microscopy.The morphological analysis revealed agglomerated spherical nanoparticles with sizes varying from 5 to 30 nm.The optical properties of the nanoparticles' band gap were characterized using diffuse reflectance spectroscopy.The band gap was found to decrease with increasing annealing temperature.The O vacancy defects were analyzed using photoluminescence spectroscopy.The increase in the crystallite size,decreasing band gap,and the increasing intensities of the UV and visible emission peaks indicated that the green-synthesized SnO2 may play future important roles in catalysis and optoelectronic devices.     

基于细菌纤维素模板制备二氧化硅纳米管

以正硅酸乙酯(TEOS)为原料、细菌纤维素为模板制备了高产率、尺寸均匀、超大长径比、具有较稳定宏观形貌的二氧化硅纳米管.借助透射电子显微镜(TEM)、扫描电子显微镜(SEM)、热失重(TGA)等分析方法对样品进行表征,探讨二氧化硅纳米管的形成机理,并考察实验条件对二氧化硅纳米管的产率和形貌等的影响.结果表明:低浓度的硅源、催化剂与较低的焙烧温度,有利于得到分散性良好的SiO2纳米管网络结构.     

Structural,morphological,and optical properties of tin(Ⅳ) oxide nanoparticles synthesized using Camellia sinensis extract: a green approach

Tin oxide(SnO_2) nanoparticles were cost-effectively synthesized using nontoxic chemicals and green tea(Camellia sinensis) extract via a green synthesis method. The structural properties of the obtained nanoparticles were studied using X-ray diffraction, which indicated that the crystallite size was less than 20 nm. The particle size and morphology of the nanoparticles were analyzed using scanning electron microscopy and transmission electron microscopy. The morphological analysis revealed agglomerated spherical nanoparticles with sizes varying from 5 to 30 nm. The optical properties of the nanoparticles' band gap were characterized using diffuse reflectance spectroscopy. The band gap was found to decrease with increasing annealing temperature. The O vacancy defects were analyzed using photoluminescence spectroscopy. The increase in the crystallite size, decreasing band gap, and the increasing intensities of the UV and visible emission peaks indicated that the green-synthesized SnO_2 may play future important roles in catalysis and optoelectronic devices.     

Microstructure and optical absorption properties of Au/NiO thin films

Au nanoparticles dispersed NiO composite films were prepared by a chemical solution method. The phase structure, microstructure, surface chemical state, and optical absorption properties of the films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Uv-vis spectrometer. The results indicate that Au particles with the average diameters of 35–42 nm are approximately spherical and disperse in the NiO matrix. The optical absorption peaks due to the surface plasmon resonance of Au particles shift to the shorter wavelength and intensify with the increase of Au content. The bandwidth narrows when the Au content increases from 8.4wt% to 45.2wt%, but widens by further increasing the Au content from 45.2wt% to 60.5wt%. The band gap E_g increases with the increase of Au contents from 8.4wt% to 45.2wt%, but decreases by further increasing the Au content.     

光隔离器隔离度的理论分析

针对影响光隔离器性能的诸多因素，基于磁致圆偏振二向色性（MCD）的理论，利用琼斯矢量和矩阵光学的方法分析了法拉第旋转角精度，材料本身的吸收以及MCD对偏振相关型光隔离器隔离度的影响，得出了它们与光隔离器隔离度的解析表达式，研究结果对光隔离器的优化设计具有一定实际意义。     

金属-石墨烯光子晶体复合结构多带光吸收器设计中金属材料的选择

研究表明,具有金属-石墨烯光子晶体-金属结构的光吸收器可实现多带吸收。这种光吸收器是在由石墨烯和介质材料构成的石墨烯光子晶体两侧加载金属层构成。所加载的金属材料的光学特性对多带吸收特性具有很大的影响。采用金属介电常数的Drude-Lorentz色散模型和传输矩阵法,比较分析了七种金属材料在可见光波段对光吸收器多带吸收特性的影响。发现金属银适合做光吸收器入射空间一侧的金属层材料,而金属铝、银、金和铜适合做衬底层材料。进一步的计算发现,只使用银做加载金属材料可实现一致性好、制作容差大、吸收带宽窄的多带光吸收器。研究结果对实际多带光吸收器的设计提供了参考。     

A multiple-labelling method for cells using Au nanoparticles with different shapes

An important and difficult issue is simultaneously identifying the detailed locations of various molecules on the cell surface, as this identification requires a synergistic effect between more than one molecule in a living cell. Au nanoparticles (NPs) with different shapes can be readily recognised under low vacuum scanning electron microscopy (lvSEM). Anisotropic Au nanorods (NRs) possess unique surface plasmon resonance (SPR) properties, which can be further utilised for two photon luminescence (TPL) and other optical imaging techniques. In this paper, Au NRs and Au nanooctahedra (Au NOs) are introduced as biomarkers for ICAM-1 and Integrin β1. Combined with the advantages of lvSEM, this multiple-labelling method is a new method for studying the interactions between specific, functional molecules.