Quantized Nanocrystalline CdTe Thin Films

Size quantized nanocrystalline semiconductor thin films have attracted considerable interest in the photoelectrochemical studies1,2. In this paper, we report a pronounced size quantization in nanocrystalline CdTe thin films which is less extensively studied.Nanocrystalline CdTe thin films were electrodeposited on conducting glass by asymmetric rectangular pulse in dimethylsulfoxide solution containing 6 mmol/L Te, 0.75 mmol/L Cd(ClO4)2, 18 mmol/L triphenylphosphine and 0.1 mol/L LiClO4 a…     

A Free Energy Model for Curved Surfaces and Curved Thin Films in Emulsions

The formulation of surface thermodynamics for flat surfaces has been done so as to be free of the Gibbs surface construction. The advantage of these formulations is that it allows the choice of thermodynamic field variables that is more general than the traditional construction. However, a generalization to curved surfaces including thin films that exist in emulsion structures has not been published. The Hansen-Cahn construction is developed in a setting that allows curvature terms to be added to the free energy expression. The Laplace equation extended to include bending elasticity and spontaneous bending elasticity is derived by computing functional derivatives of the free energy. Results for both single interfaces and double interfaces are reported. Stability conditions for profile fluctuations are developed to include these additional properties.     

Low Temperature Sol-Gel Preparation of Nanocrystalline TiO2 Thin Films

TiO₂ nanocrystalline thin films with varying degree of porosity have been prepared using a low temperature method. TiO₂ films of the anatase form have been obtained by using a polyethylene glycol (PEG) modified sol-gel method. Densification and crystallization of the films was found to result from the thermal treatment of the dip coated films in boiling water. The films have been characterized by Raman, XRD, FTIR, AFM and optical methods. Highly transparent films with transmission in excess of 85% and porosity as high as 58% are formed predominantly of anatase crystallites of dimensions of the order of 5 nm. Initial results on lithium intercalation into these films resulting in an efficient optical modulation in the visible and near infrared regions demonstrate a good potential of these films for electrochromic applications.     

Nonaggregated Zinc Phthalocyanine in Mesoporous Nanocrystalline TiO2 Thin Films

Summary: A simple sonochemical approach has been successfully developed to deposit poorly dissolved phthalocyanine dyes onto the surface of a highly‐ordered mesoporous nanostructured TiO₂ thin film. The aggregation‐free phthalocyanines are effectively encapsulated and stabilized in the nanopore arrays of the zeolite‐like mesoporous nanocrystalline TiO₂ thin film. Highly dispersed dye∥TiO₂ heterojunction arrays with a large contact area can be obtained by using this interesting approach.

The incorporation of phthalocyanine dyes into the surface of a highly‐ordered mesoporous nanostructured TiO₂ thin film, a potential photocatalyst.     

二氧化钛纳米晶薄膜的吸收光谱和激发发射光谱

由TiO₂反胶束溶胶制备一系列TiO₂纳米晶薄膜，对膜的吸收光谱和激发发射光谱研究表明制备的膜存在有二种模式的跃迁，直接跃迁和间接跃迁。由于厚膜中存在较强的表面相互作用，厚膜的直接跃迁禁带宽与薄膜相比发生了红移。在不同陈化时间，浸渍相同次数制得的膜具有相同的直接跃迁禁带宽。除浸渍一次的膜不存在间接跃迁外，所有的膜具有相同的间接跃迁禁带宽。所有的膜具有几乎相同的发射光谱模式。     

X-Ray Microanalysis of Thin Surface Films and Coatings

 The paper gives an overview of the present knowledge in the field of X-ray analysis of surface films and more generally stratified specimens. The aim of the paper is not to report the details and formulas of the available quantitative procedures, but to concentrate on the general ideas and orders of magnitude illustrating the capability and limits of the method, and on the optimal adaptation of the operating conditions to every particular problem. The various specific pitfalls which can be encountered are pointed out, in particular the fluorescence effects when using high-energy X-ray lines, or the anomalies due to chemical bonding, absorption uncertainties, and contamination effects when soft radiations are employed.     

Synthesis of Atomically Thin Boron Films on Copper Foils

Two‐dimensional boron materials have recently attracted extensive theoretical interest because of their exceptional structural complexity and remarkable physical and chemical properties. However, such 2D boron monolayers have still not been synthesized. In this report, the synthesis of atomically thin 2D γ‐boron films on copper foils is achieved by chemical vapor deposition using a mixture of pure boron and boron oxide powders as the boron source and hydrogen gas as the carrier gas. Strikingly, the optical band gap of the boron film was measured to be around 2.25 eV, which is close to the value (2.07 eV) determined by first‐principles calculations, suggesting that the γ‐B₂₈ monolayer is a fascinating direct band gap semiconductor. Furthermore, a strong photoluminescence emission band was observed at approximately 626 nm, which is again due to the direct band gap. This study could pave the way for applications of two‐dimensional boron materials in electronic and photonic devices.     

电沉积二氧化钛纳米微粒膜的光电化学性能和表面形貌研究

采用光电流谱、透射光谱和扫描微探针显微镜技术对电沉积法制备的二氧化钛纳米微粒膜的光电化学性能和表面形貌进行了研究.结果表明,不同制备条件下的二氧化钛纳米微粒膜具有与紧密的半导体电极不同的光电化学性质,并探讨了其光电化学性能与表面形貌的关系.     

钛金属表面结构可控多层钛酸盐纳米管薄膜的制备和结构稳定性

在水热条件下, 通过控制反应温度和氢氧化钠的浓度, 在钛金属表面得到结构可控的多层钛酸盐纳米管薄膜. 根据扫描电子显微镜和高倍透射电子显微镜的观测结果, 认为钛金属表面多层钛酸盐纳米管薄膜的形成经历以下4个阶段: (1) 钛金属的水合和碱性钛酸盐水凝胶的生成; (2) 碱性钛酸盐水凝胶分解并形成层状Na₂Ti₃O₇; (3) 层状Na₂Ti₃O₇的生长; (4) 层状Na₂Ti₃O₇的劈裂和多层卷曲成轴形成纳米管. 研究了薄膜形成后机械处理对薄膜形貌和结构稳定性的影响, 并利用超声的方法实现了多层膜的层分离.     

Effect of Surface Roughness on Structure and Dynamics in Thin Films

We performed Monte Carlo simulations of free‐standing, amorphous polyethylene (PE) thin films at 509 K. The three films are constructed from 9, 36, or 144 independent parent PE chains, with 100 carbon atoms per chain. The two‐dimensional periodic cross‐sectional area of the simulation box is proportional to the number of independent parent chains, with the 144‐chain film having an area four times larger than the 36‐chain film. All three films have a similar bulk density and a comparable thickness between the two free surfaces. The 144‐chain film with the largest periodic surface area has a broader density profile due to the increased roughness of its surfaces. Snapshots of its surfaces along the trajectory indicate dynamic changes in the high and low regions of the rough surfaces. Diffusion of the chains parallel to the free surfaces is suppressed in the 144‐chain film, due to increased surface roughness. The tendency of bonds to orient parallel to the free surface is less pronounced in films with higher surface roughness.     

Micropatterning of Sol-Gel Derived Thin Films Using Hydrophobic-Hydrophilic Patterned Surface

Formation process of convexly shaped oxide micropatterns using hydrophobic-hydrophilic patterned surface has been examined, and this technique was applied to several oxide thin films such as SnO₂, ZrO₂, TiO₂ and Al₂O₃. Hydrophobic-hydrophilic patterned surfaces were prepared on glass substrates by selective UV irradiation through a photomask on double-layered films of a very thin TiO₂ gel film as the underlayer and a hydrolyzed fluoroalkyltrimethoxysilane layer as the top layer. Precursor solutions were then spin-coated on the hydrophobic-hydrophilic patterns, and the coated substrates were dried at room temperature. The micropatterns of oxides were very difficult to be formed on the hydrophobic-hydrophilic patterned surfaces from metal-alkoxides as a precursor solution, but convexly shaped micropatterns were formed on the hydrophilic regions of the pattern when metal chlorides or oxychlorides were used as starting materials. This patterning technique potentially has a wide variety of applications such as fabrication of micro-optical components and finely patterned transparent electrodes.     

基于铁薄膜的表面等离子体耦合定向荧光研究

本文报道了以纳米铁膜为基底的SPCDF检测方法. 以荧光素和卟啉为例, 探讨了SPCDF信号的特性, 在固定角度下检测了荧光素-卟啉双荧光团体系的SPCDF信号, 并应用于全血样品的分析.     

纳米多孔金薄膜的表面等离子体共振传感特性

对淀积在玻璃衬底上厚度约60 nm的金银合金溅射薄膜进行硝酸腐蚀脱银处理, 得到纳米多孔金薄膜. 利用自建的波长检测型表面等离子体共振(SPR)传感装置研究了腐蚀时间对纳米多孔金薄膜SPR特性的影响, 结果发现纳米多孔金薄膜与水溶液接触后在400-900 nm光谱范围内不具有SPR效应, 而当薄膜置于空气中时会产生明显的传播等离子体共振吸收峰, 其共振波长随腐蚀时间增加逐渐红移. 纳米多孔金薄膜在空气气氛中的SPR效应使其能够用于原位监测气相分子在孔内的吸附, 还可对在液相中吸附的生化分子进行离位测试. 本文对L-谷胱甘肽、L-半胱氨酸、2-氨基乙硫醇三种含巯基的生化小分子在纳米多孔金薄膜内的吸附进行了离位分析, 结果表明与传统的致密金薄膜SPR芯片比较, 纳米多孔金薄膜对这些分子显示出更高的灵敏度和更低的检测下限, 这归功于多孔金的大比表面积使其能够吸附大量的生化小分子. 实验还对乙醇蒸气在纳米多孔金薄膜内的吸附进行了原位监测, 发现吸附平衡所用时间较长, 约为160 min.     

蒽醌类染料的合成及其薄膜性能

合成了两种带不同取代基的蒽醌类衍生物．用扫描量热法测定了它们的晶化温度，用６３２．８ｎｍ处非晶态和晶态的反射率计算这两种化合物的反衬度分别为２０％和６０％，并用扫描电子显微镜观察了相变前后晶粒的变化．     

Synthesis of Transparent Mesoporous and Mesostructured Thin Silica Films

A novel method for obtaining crack-free transparent periodic mesoporous thin films is described. Such films are prepared by a simple sol-gel process using surfactants as templates, with a pre-treatment of the glass substrate. The silicate precursor (tetraethoxysilane) is pre-hydrolyzed under acidic conditions before dissolving directly cetyltrimethylammonium bromide (CTAB). The solution is then spin-coated on pre-treated glass substrate. After the film has been deposited, it is calcined in air. X-ray Diffraction (XRD) has been used to characterize the film before and after thermal treatment. The film consists of a nanocomposite material with a periodic structure. Before calcination the XRD pattern has a sharp peak at d = 3.8 nms which is broadened and shifted by about 3.0 nm after calcination. Infrared transmission spectra have been performed on the films. Analysis of the free OH group stretching vibration indicates the removal of the surfactant after calcination in addition to an enhancement of the specific surface area.     

Naphthenic Acid-Derived Nanocrystalline ZnO Films on Silica Substrate

Sol–gel-derived nanocrystalline ZnO thin films on silica glass substrates were prepared by using a zinc naphthenate precursor. As-deposited films were heat treated at 500, 600 and 700°C for 30 min in air. The ZnO films were analyzed by X-ray diffraction, field emission—scanning electron microscope, scanning probe microscope, and ultra violet—visible—near infrared spectrophotometer. With an increase in heat treatment temperature, the peak intensity of (002) plane increases. No evidently aggregated particles are present. All the films exhibit a high transmittance (>80%) in visible region and show a sharp fundamental absorption edge at about 0.38–0.40 m. The estimated energy band gap for all the films are within the range reported for films and single crystal.     

氧化铁薄膜的水热合成及其光电转换性能

通过水热方法在掺杂氟的SnO2(FTO)导电玻璃上制备了不同形貌的氧化铁薄膜。利用无机铁盐浸渍法在FTO玻璃上进行氧化铁晶种的预处理使得所制备的氧化铁薄膜更致密且均一。研究了表面活性剂对氧化铁晶体形貌的影响。使用十二烷基苯磺酸钠(SDBS)和三嵌段聚合物P123做为形貌导向剂分别得到棒状和四方体形貌的氧化铁薄膜。氧化铁薄膜可调的形貌可能是由于表面活性剂和铁氧团簇的组装或者某些晶面吸附了阴离子而改变了生长速率引起的。同时,研究了其光电性能,具有四面体形貌的氧化铁薄膜可以产生较大的光电流,这是由于其缩短了光生空穴的扩散距离。     

金刚石薄膜电化学

金刚石由于其特殊的物理与化学性质,早在几百年前就吸引了人们对它的关注.化学气相沉积(chemical vapor deposition,CVD)法制备的高掺杂硼复合多晶金刚石薄膜,为金刚石薄膜在电化学中的应用开辟了新的领域.作为新型碳素电极材料,高掺杂硼复合多晶金刚石薄膜具有许多目前使用的电极材料所不可比拟的优异特性如:宽电化学势窗,低残留电流,极好的电化学稳定性以及表面不易被污染等.本文综述了高掺杂硼复合多晶金刚石薄膜电极在电化学中的几个重要应用,包括电分析、电合成及电化学法处理废水等.     

Plasma-Chemical Synthesis of Lead Sulphide Thin Films for Near-IR Photodetectors

Plasma Chemistry and Plasma Processing - Lead sulfide (PbS) thin films of different morphology were synthesized via direct interaction of lead and sulfur vapors. Low temperature nonequilibrium RF...