Ag2Se纳米材料的制备方法

对纳米Ag2Se的化学制备方法进行了概述,着重介绍了模板法、声化学法、水(溶剂)热法、光照合成法、微乳状液法等;展示了新近得到的不同形貌和性质的As2Se纳米晶体;并对其发展趋势和应用前景进行了展望.     

Thin films of vanadium oxide grown on vanadium metal: oxidation conditions to produce V2O5 films for Li‐intercalation applications and characterisation by XPS,AFM, RBS/NRA

Thin films of vanadium oxide were grown on vanadium metal surfaces (i) in air at ambient conditions, (ii) in 5 mM H₂SO₄ (aq), pH 3, (iii) by thermal oxidation at low oxygen pressure (10^?5 mbar) at temperatures between 350 and 550 °C and (iv) at near‐atmospheric oxygen pressure (750 mbar) at 500 °C. The oxide films were investigated by atomic force microscopy (AFM), X‐ray photoelectron spectroscopy (XPS), X‐Ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). The lithium intercalation properties were studied by cyclic voltammetry (CV). The results show that the oxide films formed in air at room temperature (RT), in acidic aqueous solution, and at low oxygen pressure at elevated temperatures are composed of V₂O₃. In air and in aqueous solution at RT, the oxide films are ultra‐thin and hydroxylated. At 500 °C, nearly atmospheric oxygen pressure is required to form crystalline V₂O₅ films. The oxide films grown at pO₂ = 750 mbar for 5 min are about 260‐nm thick, and consist of a 115‐nm outer layer of crystalline V₂O₅. The inner oxide is mainly composed of VO₂. For all high temperature oxidations, the oxygen diffusion from the oxide film into the metal matrix was considerable. The oxygen saturation of the metal at 450 °C was found, by XPS, to be 27 at.% at the oxide/metal interface. The well‐crystallized V₂O₅ film, formed by oxidation for 5 min at 500 °C and 750 mbar O₂, was shown to have good lithium intercalation properties and is a promising candidate as electrode material in lithium batteries. Copyright © 2005 John Wiley & Sons, Ltd.     

Development of cerium‐based conversion coatings on 2024‐T3 Al alloy after rare‐earth desmutting

The deposition of Ce‐based conversion coatings onto 2024‐T3 Al alloy sheet was studied using Rutherford backscattering spectroscopy, scanning electron microscopy, Auger electron spectroscopy, x‐ray photoelectron spectroscopy and atomic force microscopy. The Al sheet was pretreated with an alkaline clean followed by treatment in a Ce(IV) and H₂SO₄‐based desmutter. The Ce(IV)‐based conversion coating solution contained 0.1 M CeCl₃·7H₂O and 3% H₂O₂ and was acidified to pH 1.9 with HCl. Upon immersion, there was an induction period that included activation followed by aluminium oxide growth over the matrix and cerium oxide deposition onto cathodic intermetallic particles and along rolling marks on the surface. After the induction period cerium oxide deposited generally across the whole surface and thickened. The strongest anodic sites initially were adjacent to the intermetallic cathodes and resulted in aluminium dissolution but also oxide thickening. Copyright © 2004 John Wiley & Sons, Ltd.     

Surface Characterisation of Cerium-Doped Silica Coatings Obtained by Sol-Gel

The chemical composition of cerium-doped silica coatings prepared via sol-gel were studied using X-ray photoelectron spectroscopy (XPS) in conjunction with Ar⁺-ion sputtering, Rutherford back-scattering spectroscopy (RBS) and photoluminescence (PL) spectroscopy. XPS results showed that cerium was incorporated in the silica network as Ce(III). The absence of PL emissions from Ce(III) was explained by a clustering of the ions producing a quenching of the luminescence. XPS combined with Ar⁺ and RBS showed that the distribution of Ce is not uniform across the coating, showing a maximum concentration in an inner layer of the coating.     

肌红蛋白在硅基表面自组装的研究

通过自组装、自组织及自我复制构筑生物分子和纳米结构在自然界和非自然界相当普遍。利用半导体材料硅片或与硅相关的物质(二氧化硅等)为基底制备SAMs(Self-assembled Monolayers)的技术是一项很有前景的有机功能膜制备技术。由于这类SAMs的有序性和常温下的高稳定性,尤其是所     

XPS and atomic force microscopy of plasma-treated polysulfone

Surface treatment of polysulfone by O₂, H₂, He, Ne, Ar, and CF₄ nonisothermal glow discharges has been investigated by x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The chemical and topographical modification of the surface is found to be strongly influenced by the type of feed gas employed. © 1996 John Wiley & Sons, Inc.     

Quantitative AES,XPS and RBS determination of intergranular bismuth coverage in copper bicrystals at 500 °C

We report on a comparative measurement of intergranular bismuth coverage on a copper substrate using Auger electron spectroscopy (AES), x‐ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). Bicrystalline copper samples were put in presence of bismuth vapour at 500 °C (consequently embrittled by the grain‐boundary penetration of Bi atoms), water‐quenched and subsequently fractured at room temperature. Each fracture surface was analysed by AES, XPS and RBS with the help of quantitative procedures developed for each of the three techniques. All possible sources of discrepancy were carefully examined. The combined quantitative approaches have led to excellent agreement. Such a good agreement constitutes a necessary condition to begin a critical discussion on the mechanisms potentially involved in the liquid metal embrittlement (LME) phenomenon. Copyright © 2005 John Wiley & Sons, Ltd.     

Stabilization mechanism of TiO2 on flexible fluorocarbon films as a functional photocatalyst

The repetitive discoloration kinetics of the azo-dye Methyl Orange (taken as a model organic compound) was followed under solar simulated radiation (90 mW/cm²) to assess the performance of the TiO₂/Tedlar^® composite photocatalyst. The influence of solution parameters on the photo-discoloration process: pH, dye concentration, applied light intensity and concentration of H₂O₂ were systematically investigated. During the photocatalysis a modification occurs in the TiO₂/Tedlar^® composite due to the TiO₂ interaction with the Tedlar^® film. Physical insight is given for the stabilization mechanism of the TiO₂ particles in the Tedlar matrix based on the data obtained by X-ray photoelectron spectroscopy (XPS). The F 1s peak of the Tedlar film indicates that the TiO₂ is loaded on the Tedlar fluoro-groups. The loading of TiO₂ on the 75 μm thick Tedlar^® film was 0.9% (w/w) as determined by atomic absorption spectrophotometry (AAS). Attenuated total reflection infrared spectroscopy (ATRIR) shows no formation of additional bands within the photodiscoloration reaction. This shows that an efficient catalysis taking place on the TiO₂/Tedlar^® surface. The rugosity (mean square roughness, rms) of the TiO₂/Tedlar^® film was determined by atomic force microscopy (AFM) to be 19.7 nm. This value remained constant during long-term operation. Transmission electron microscopy (TEM) reports the thickness and coverage of TiO₂ Degussa P-25 on the Tedlar^® surface before and after photocatalysis.     

Synthesis of Various Types of Silver Nanoparticles Used as Physical Developing Nuclei in Photographic Science

Ag nanoparticles used as physical developing nuclei in photographic science were prepared by reduction method.The as-formed Ag nanoparticle colloid was characterized by UV-Vis absorption spectrum.Atomic Force Microscopy(AFM) and Charge Coupled Device(CCD) technique.It is found that the source of Ag ions,the addition of surfactant and polymer,all have great influence on the size,topography and catalytic activity of Ag nanoparticles.     

Effect of protein solution components in the adsorption of Herbaspirillum seropedicae GlnB protein on mica

The adsorption of proteins and its buffer solution on mica surfaces was investigated by atomic force microscopy (AFM). Different salt concentration of the Herbaspirillum seropedicae GlnB protein (GlnB-Hs) solution deposited on mica was investigated. This protein is a globular, soluble homotrimer (36 kDa), member of PII-like proteins family involved in signal transducing in prokaryote. Supramolecular structures were formed when this protein was deposited onto bare mica surface. The topographic AFM images of the GlnB-Hs films showed that at high salt concentration the supramolecular structures are spherical-like, instead of the typical doughnut-like shape for low salt concentration. AFM images of NaCl and Tris from the buffer solution showed structures with the same pattern as those observed for high salt protein solution, misleading the image interpretation. XPS experiments showed that GlnB protein film covers the mica surface without chemical reaction.     

Trimethylsilylcellulose synthesis revisited

A simplification of the overall method of producing trimethylsilylcellulose solutions in common organic volatile solvents is reported. Microcrystalline cellulose was derivatized aiming its solubilization in tetrahydrofuran and toluene to obtain ultra-thin films of cellulose by spin-coating. The main simplifications are: 1) elimination of a swelling step before dissolution in the binary solvent N,N-dimethylacetamide/LiCl by using microcrystalline cellulose; 2) derivatization of cellulose –OH groups with –Si(CH₃)₃ groups was successful with no additional catalyst, like trimethylsilyl chloride, the degree of substitution (DS) being 2.2 ± 0.1. The DS at the extreme surface of the films was computed from the X-ray Photoelectron Spectroscopy data: using solely C 1s fitted component areas and, alternatively, from both C 1s and Si 2p areas. The DS estimated with a technique specific of the surface is close to the bulky one obtained from gravimetric measurements reported in the literature for materials synthesized with catalyst. The topographic uniformity is shown by Atomic Force Microscopy.     

活性胃蛋白酶在阳离子化PET 表面的自组装功能膜研究

利用分子沉积法在表面阳离子化的聚对苯二甲酸乙二酯基材上制备活性胃蛋白酶分子的自组装生物膜,并利用原子力显微镜和X-射线光电子能谱对基材和活性胃蛋白酶/PET-NH3^ 组装膜的表面形貌及组分进行了研究。