CdS纳米粒子与半胱氨酸相互作用的研究

合成了粒径均匀和分散性好的CdS纳米粒子.通过改变CdS纳米粒子及半胱氨酸的浓度、体系的pH值及CdCl2和CH3CSNH2摩尔比等实验条件跟踪监测了CdS纳米粒子光谱性质的变化,探讨了CdS纳米粒子与半胱氨酸之间的相互作用及化学反应机理.     

掺铕GaN薄膜的Raman散射研究

采用金属有机物化学气相沉积（MOCVD）和离子注入的方法制备了掺铕GaN薄膜。利用Raman散射技术研究薄膜的晶格振动，从而确定离子注入引进的晶格损伤变化情况。结果表明，Eu离子注入剂量越大，对晶格的损伤越严重；Eu离子注入的能量越高，对晶格的损伤也越严重；采用沟道注入方法可以有效地减小对晶体的损伤。离子注入后进行高温退火，可以使晶格中的Ga空位引起的缺陷得到有效的恢复。而N空位引起的缺陷随着退火温度的升高先减少后增多。不同几何配置的Raman谱研究表明，1000℃的高温退火导致了GaN的分解。     

CdS/TiO2复合纳米粒子的光学性质

在Brij35/正己醇/环己烷/水构成的反相微乳体系中，分别合成了CdS、TiO2纳米粒子和TiO2包覆CdS（CdS/TiO2）的复合纳米粒子.测定了它们的紫外-可见吸收和荧光光谱.结果表明， CdS/TiO2复合纳米粒子在可见光区的吸收比相应的两组分的吸收之和更强.纳米CdS和纳米TiO2均有较强的荧光.而且在相同浓度时纳米TiO2的荧光比纳米CdS的荧光更强.但在CdS/TiO2复合纳米粒子中，TiO2的荧光被淬灭，而CdS的荧光稍有降低.     

甲苯-乙二醇两相界面反应合成CdS纳米粒子

以十八胺为表面修饰剂,硬脂酸镉和硫脲为前驱物,在甲苯-乙二醇两相界面处合成了CdS纳米粒子.研究了反应时间、前驱物浓度、前驱物和表面修饰剂摩尔比等因素对合成CdS纳米粒子的影响.采用紫外-可见吸收光谱、荧光光谱、透射电子显微镜(TEM)和广角X射线衍射(WAXD)等方法对CdS纳米粒子的光学性质、形貌及晶体结构进行了表...     

CdS/SiO2纳米棒核/壳结构的制备和发光性能

利用在醇介质中氨水催化水解硅酸乙酯（TEOS）制备SiO2来包覆半导体CdS纳米棒而形成CdS/SiO2核/壳结构.通过X射线衍射（XRD）、透射电子显微镜（TEM）证实SiO2包覆壳层为非晶，且壳层厚度随TEOS浓度的增大而增加，在10～30 nm之间.并研究了其紫外 可见吸收光谱（UV Vis）和荧光发射光谱(PL)的性质.     

水溶性CdSe/CdS核壳纳米粒子制备的影响因素及其对CdSe/CdS光谱特性的影响

以半胱氨酸镉配合物为前体, 在水溶液中合成CdSe纳米粒子, 以CdS对其表面进行修饰, 得到具有核壳结构的CdSe/CdS 纳米粒子. 采用XRD, TEM表征其结构及形貌; 以荧光光谱研究了时间、pH值、壳量、壳前体加入方式、稳定剂用量等因素对CdSe/CdS光谱特性的影响.     

CdS纳米粒子的水热微乳法制备

0引言CdS是一种重要的Ⅱ-Ⅵ族半导体,其独特的光电化学性能引起人们的广泛关注,而其性能与晶粒尺寸、晶体结构等密切相关,因而CdS的纳米结构的研究备受关注[1￣3]。目前,制备CdS纳米粒子的主要方法有溶剂热法[4],化学浴沉积法[5],微乳液法[6]等。微乳液是合成球形纳米粒子的良好介质,具有实验装置简单,操作方便,应用领域广并且有可控制微粒的粒度等优点[7]。但其在室温条件下合成的CdS粒子的结晶性较差,严重影响其光电性能。Gan和Liu等[8]曾在NP5-NP9/PE/SOL微乳液中,在室温及水热条件下合成ZnS:Mn发光纳米材料,来提高在微乳液中制…     

新型CdS/TiO2纳米复合材料的制备及其可见光催化性能研究

采用浸渍法和水热法相结合制备了新型的CdS/TiO₂纳米复合材料,并采用X射线衍射(XRD)、透射电子显微镜(TEM)、UV-Vis吸收光谱(UV-VIS)、电子自旋共振谱(ESR)等对样品进行了表征,XRD、TEM表明所制备的新型CdS/TiO₂粒径小、分散均匀,TiO₂以锐钛矿型存在,CdS以高分散的立方相和六方相存在,对比直接法制备的CdS/TiO₂,新型的CdS/TiO₂对活性艳红X-3B具有明显提高的可见光催化活性;大量的束缚单电子氧空位及电子之间强相互作用是新型CdS/TiO₂可见光催化活性提高的主要原因.     

纳米级SiO2填充PVC/CPE复合材料研究

80年代以后发展起来的纳米材料被称为"21世纪最有前途的材料",已成为材料学中跨世纪的研究热点[1].纳米级无机粒子/聚合物复合材料是纳米材料中的一种具有重要价值的新型材料,可广泛应用于橡胶、塑料、纤维三大合成材料之中[2].其中,纳米级SiO2是纳米材料中的重要一员,它被称作跨世纪的高科技材料[3].因此, 本文就纳米级SiO2填充PVC/CPE复合材料进行探讨.     

二维凝聚体系中单轴承向分子的偏振Raman散射强度

分析子薄膜体系几种常用测量坐标下的偏振Raman散射强度表达式，发现当测量坐标与膜坐标重叠时，各种偏振Raman散射强度只需用膜坐标中的Raman散射活性来表达，如果这两个坐标不重叠，需进一步求出膜坐标中Raman张量元二次交叉项的平均值，本文给出了单轴唯一角取向模型这了些二次交叉项的平均值表达式及取向分布模型下膜坐禁中所有Raman张量元二次项平均值。     

Confinement of CdS Nanocrystals in a Sonogel Matrix

CdS/silica xerogel composites have been prepared using a sonocatalytic method. The confinement effects of CdS semiconductor nanocrystallites have been analyzed through UV-VIS absorption and Raman scattering. The blue shift of the absorption band and the shape of the Low Frequency Inelastic Raman Scattering (LOFIRS) spectra make it possible to evaluate the size of nanocrystallites, which are contrasted with previous results obtained through other techniques. Moreover, in the 200–700 cm^–1 region of Raman shift, resonant effects are discussed, through the longitudinal optical mode lines.     

乐果涂膜表面增强拉曼光谱研究

通过蒸发乐果饱和水溶液在磁控溅射银膜上形成乐果涂膜,利用表面增强拉曼光谱(SERS)技术研究了乐果涂膜的分子振动特性,并与乐果固体拉曼谱进行比较。研究结果表明,乐果晶体结构长程有序性的破坏造成涂膜SERS体系中υ(P—S)和υ(PS)振动峰的展宽和蓝移,水解引起乐果δ(SPOC)和δs(COPOC)振动模式强度降低,OC—N键中的O原子和N原子以及水解质子化的O在银表面吸附造成υ(OC—N)、υ(OC)、δ(N—H)、υ(CN)、δ(C—N—C)、δ(OPO)和υ(P—O)等振动模式显著增强。这为利用SERS技术研究乐果溶液以及乐果在植物体、食品中的残留提供了实验和理论依据。     

Size Dependence of First-order Hyperpolarizability of CdS Nanoparticles Studied by Hyper-Rayleigh Scattering

The second-order optical nonlinearity of CdS nanoparticles with different diameters of 28.0, 30.0, 31.5, 50.0, and 91.0 A was studied by hyper-Rayleigh scattering technique. Results show that the first-order hyperpolarizability P value per CdS partiele decreases as size is reduced to diameter of 31.5 A; however, as CdS size further decreases, this trend is reversed and (J value increases. Substantially, the normalized P value per CdS formula unit, β0, exhibits systematic enhancement with decreasing size. This phenomenon is interpreted in terms of a so-called surfaee contribution mechanism.     

表面增强拉曼散射活性基底

表面增强拉曼散射(SERS)是人们将激光拉曼光谱应用到表面科学研究中所发现的异常表面光学现象。它可以将吸附在材料表面的分子的拉曼信号放大106到1014倍,这使其在探测器的应用和单分子检测方面有着巨大的发展潜力。由于分子所吸附的基底表面形态是SERS效应能否发生和SERS信号强弱的重要影响因素,所以分子的承载基体是很关键的,因而SERS活性基底的研究一直是该领域的研究热点之一。本文总结了形态各异的表面增强拉曼散射活性基底,分析了最新发展并对其未来作一展望。     

Raman and Surface-enhanced Raman Scattering of Chlorophenols

Raman spectrum is a powerful analytical tool for determining the chemical information of compounds. In this study, we obtained analytical results of chlorophenols(CPs) molecules including 4-chlorophenol(4-CP), 2,6-dich- lorophenol(2,6-DCP) and 2,4,6-trichlorophenol(2,4,6-TCP) on the surface of Ag dendrites by surface-enhanced Raman scattering(SERS) spectra. SEM images indicate that the SERS substrate of Ag dendrites is composed of a large number of polygonal nanocrystallites, which self-assembled into a 3D hierarchical structure. It was found that there were distinct differences for those three molecules from Raman and SERS spectra. This indicates that SERS could be a new tool of detection technique regarding trace amounts of CPs.     

Surface-enhanced Raman Scattering of Self-assembled Superstructures

Surface-enhanced Raman scattering(SERS) is a molecular specific spectroscopic technique that amplifies the Raman signal of absorbed molecules for up to 10¹⁰times. Over the past decades, SERS substrates experienced rapid growth, resulting in excellent development for SERS analysis. Because the surface plasmonic resonance coupling between individual materials can form a "hotspot" region to maximize the Raman signal, among many substrate construction strategies, self-assembly attracts more attention in constructing superstructures with strong, uniform and stable SERS activity. In addition, a number of plasmon-free nanomaterials with appropriate superstructures samely show enhanced SERS activity, which is primarily attributed to the formation of the optical resonator. This review aims to provide a scientific synopsis on the progress of self-assembled superstructures for SERS and ignite new dis˗ coveries in the SERS platform, as well as SERS applications in various fields.     

Raman Scattering Activities for Uniaxially Oriented Molecules

Raman scattering activities were derived for uniaxially oriented molecules. The unique axis of the molecules is assumed to rotate around one of the axes of space-fixed coordinate in a fixed orientation angle with respect to the axis, while the other two principal axes of the molecules are randomly oriented. Expressions for Raman scattering activities in terms of the elements of derived polarizability tensor are given as the function of orientation angle and are tabulated for various symmetries of point groups.     

新型一氧化氮表面增强拉曼光谱探针

合成了一种含邻苯二胺的偶氮染料, 同时邻苯二胺在氧气存在条件下与一氧化氮(NO)反应生成苯并三氮唑结构, 可很好地吸附在纳米银的表面, 产生强表面增强拉曼光谱(SERS), 实现溶液中NO的检测. 实验中考察了染料浓度、纳米银溶胶团聚和溶液pH值等因素的影响. 实验结果表明, 随着NO的加入, 体系的SERS信号在1200~1700 nm之间发生了明显的变化, 其中在1300 nm左右新出现一个很强的峰. 该方法检测灵敏度可达到10-8 mol/L, 且适应的pH值范围在4.5~7.5之间, 符合生理环境要求.     

Raman Scattering Study on Vibrational Modes and Structure of Lanthanum Tellurite Glasses

Raman spectra of xLa₂O₃-(1-x)的TeO₂(x=0、0.05、0.10、0.15、0.20和0.25) lanthanum tellurite glasses were measured and analyzed over the entire glass-forming region in an effort to quantitatively follow the structural changes caused by lanthanum oxide variation. For the first time, systematic intensity measurements have been performed to elucidate the composition induced structural changes in the high-frequency stretching vibration region and a possible mechanism was proposed. The network structure of the glasses is formed by mixing TeO₄ trigonal bipyramid and TeO₃ trigonal pyramid units. The change of the lanthanum oxide content results in conversion of the TeO₄ units to TeO₃ units with a varying number of non-bridging oxygen atoms. Analysis of the Raman band contours in terms of vibrations due to different oxygen bridged trigonal bipyramid and trigonal pyramid tellurite structural units, allowed to calculate the relative amounts of the species involved in the structural changes with composition. The fraction of the terminal oxygen atoms has been estimated from the Raman intensities with the aid of a structural model concerning the structure of tellurite network systems. The simulation of the experimental density of lanthanum tellurite glasses with modifier content up to 25% revealed that the short range order building units assumed here are sufficient to account for the overall structure in these glasses.     

New elaboration of Na2O-B2O3-SiO2 glass doped with CdS nanocrystals from gel formed in aqueous solution

A new route for preparing a CdS doped sodium borosilicate glass from a gel formed in an aqueous solution is described. This elaboration process allows the preparation of a gel which starts densifying at 400°C just after the Cd sulphurizing process ensuring the protection of crystallites from oxidation. The densification of the matrix is completed at the fusion temperature (730°C), which is low enough to reduce the coalescence of the crystallites. Microstructural and optical characterization of the CdS doped glasses indicate that the crystallite size depends upon the Cd concentration. A model to calculate the crystallite size from optical absorption spectra is proposed. It indicates that the average sizes of crystallites range from 11 nm for a concentration of 0.03 mol% Cd to 3.7 nm for 0.016 mol% Cd.