Mo2C膜表面粗糙化规律的计算机模拟

引入晶粒边界修正,改进了Mo2C膜表面粗糙化物理模型,将DT2模型推广到包括有温度的情况,对Mo2C膜表面形态进行计算机模拟并统计模拟图的高度分布,确定表面粗糙度随沉积时间和基底温度的变化规律。结果表明：引入晶粒边界修正大大促进了理论与实验结果的一致,Mo2C膜表面粗糙化属快速粗造化,粗造度随基底温度升高而非线性地增大。     

薄膜表面的分形特征

在计算机上用随机数相加的方法产生了一个分形表面,对这个表面的模拟测量表明,z方向分辨率变化对分形维数测量结果影响很小,x、y方向分辨率降低时会导致测量结果统计误差增大用扫描隧道显微镜（STM）测量了沉积在三种不同基底上的Au膜的分形维数．测得Au／陶瓷的分形维数D＝2.15,Au／光学玻璃的分形维数D＝2.06．Au／载玻片上各点的分形维数较不一致．同时讨论了多图方法中各单图曲线之间不衔接的原因．     

MoS^2^-~4在铜表面的配位化学反应

MoS^2^-~4与铜表面作用可以形成几种颜色的簇合物膜。FT-IR, XPS和AES结果表明, 膜中存在Cu-S-Mo键; 簇合物膜含Cu, Mo, S, O四种元素, 分别呈+1, +6,-2, -2价, 并含少量+4和+6价硫; 膜为多分子层的双层结构 . 反应时间越长, 膜越厚;加热后膜层仍含Cu, Mo, S, O 元素, Mo向内层渗透, S则在表面富集, Cu呈+1和+2价, S呈-2, +4, +6价, Mo和O价态不变;膜层是多组分的复杂体系; 其颜色是各化合物吸附、叠加的结果。     

MoS^2^-~4在铜表面的配位化学反应

MoS^2^-~4与铜表面作用可以形成几种颜色的簇合物膜。FT-IR, XPS和AES结果表明, 膜中存在Cu-S-Mo键; 簇合物膜含Cu, Mo, S, O四种元素, 分别呈+1, +6,-2, -2价, 并含少量+4和+6价硫; 膜为多分子层的双层结构 . 反应时间越长, 膜越厚;加热后膜层仍含Cu, Mo, S, O 元素, Mo向内层渗透, S则在表面富集, Cu呈+1和+2价, S呈-2, +4, +6价, Mo和O价态不变;膜层是多组分的复杂体系; 其颜色是各化合物吸附、叠加的结果。     

基于碳化钼的燃料电池阴极催化剂的制备及其作用机理

以 Mo2C/VC 作为质子交换膜燃料电池氧还原催化剂, 并采用单电池和电化学循环伏安扫描技术考察了其氧还原活性,同时结合 X 射线衍射和 X 射线光电子能谱对其电催化机理进行初步分析. 结果表明, Mo2C/VC 对氧还原也具有电催化活性, 在 0.34, 0.45 和 0.55 V 处出现三对可逆的氧化还原峰. Mo2C/VC 的体相为β-Mo2C, 表相为+δ价(5 ≤δ≤ 6)的 MoOxCy 和 MoOz. Mo2C/VC 的电催化性能可能是由于其表面钝化物种(MoOxCy 和 MoOz)的氧化还原, 以及氧在 Mo2C 晶格中的迁入和迁出引起的.     

碳化终温对碳化钼的制备及甲烷二氧化碳重整催化性能的影响

以MoO3为前驱物, 于20%CH4-80%H2的混合气体(100 mL/min)中, 在不同设定终温下进行碳化, 制备了一系列不同碳化终温的Mo2C, 通过XRD和XPS等手段进行了表征, 并对其甲烷二氧化碳重整(DMR)制备合成气的催化性能进行评价, 讨论了碳化终温作为Mo2C的制备参数, 与所制备的Mo2C体相、表面特征和催化剂性能的关系. 结果表明, 碳化终温在700 ℃以上制得的Mo2C催化剂晶相为较纯的β-Mo2C, 随着碳化终温的升高, 催化剂碳化程度不断提高, 表面的自由碳不断增多, 碳化终温为800 ℃时为最佳, 所制备的Mo2C催化剂碳化程度较高, 表现出最佳的催化性能, 同时催化剂表面自由碳较为适量, 促进了Mo2C催化剂的碳化和氧化平衡, 有利于催化剂的活性和稳定性.     

钢表面彩色Mo-S-Fe簇合物膜

研究MoS₄^2-在钢表面发生配位化学反应所形成的具有装饰效果的多种彩色簇合物膜。FT-IR、F-IR、FT-Raman、 XPS和AES分析表明簇合物膜由Fe、Mo、 S、 O元素组成,在膜表面铁以Fe(Ⅲ)、钼以Mo(Ⅵ)状态存在,而在膜内层以Fe(Ⅱ)、Mo(Ⅳ)和Mo(Ⅵ)共存,S和O都呈-2价。从AES深度分布曲线的组成恒定区求得了各元素的相对原子百分浓度和膜层厚度,反应时间越长,膜越厚,膜为多分子层结构。     

光谱法研究钢铁表面彩色Mo-S-Fe簇合物膜

研究MoS4^2-在钢铁表面发生配位反应形成的具有装饰效果的多种彩色Mo-S-Fe簇合物膜。FT-IR、F-IR、FT-Raman、XPS和AES分析表明,簇合物膜以Fe(Ⅲ)、Mo(Ⅵ)状态存在,膜内层以Fe(Ⅱ)、Mo(Ⅳ)和Mo(Ⅵ)共存,S和O都-2价,膜表面含少量 4、 6价硫。从AES深度分布曲线的组成恒定区求得各组成元素的相对原子百分比浓度和膜层厚度,反应时间越长,膜越厚,膜为多分子层结构。加热后膜层所含元素种类及价态不变,但元素分布有所改变。     

单官能团单体C存在下A_2-B_2型缩聚产物的分子量分布

分别以概率统计方法和Monte Carlo模拟获得了单官能团单体C存在下A_2-B_2型线型缩聚产物的分子量分布。Monte Carlo方法与统计计算得出一致的结果,表明建立的Monte Carlo模型是合理的。研究了单官能团单体C的反应活性对缩聚产物分子量分布的影响,对反应体系中存在的各种不同的分子类型的消长情况分别进行了动态模拟。     

Mo2C/Al2O3催化剂用于甲烷部分氧化(POM)制合成气的研究

制备了一系列不同Mo2C担载量的Mo2C／A1203催化剂，利用微型固定床反应器对其POM反应进行了活性评价，并采用XRD、SEM和BET等方法进行了结构表征．实验结果表明，纯Mo2C催化剂在反应初期有较高的CH4转化率，但CO和H2的选择性很低，随着反应时间的增加，CH4转化率急剧下降．Mo2C担载量小于24．8％的催化剂，随担载量增加，CH4转化率明显升高．同时，随着反应时间的增加，CH4转化率有所下降，CO和H2的选择性则明显升高．Mo2C担载量在35．4％—42．5％的催化剂，具有好的CH4转化率和CO、H2选择性，但担载量过高时，CH4转化率会随反应时间的增加而下降．结构表征表明，未担载的和担载的碳化物催化剂均为β-Mo2C，担载量小于10．6％时，Mo2C高度分散于A12O3表面，担载量较高时，Mo2C颗粒变大，比表面减小．     

电色谱塔板高度方程的推导

比较了电色谱与高效液相色谱在动力学过程方面的异同。从热传导方程出发导出在有源无限长均匀圆柱体内温度场分布函数及组分移动速度径向分布函数,进而导出了温度场导致谱带弥散的弥散系数Ｄ热。提出了较全面地反映电色谱动力学过程的塔板高度方程,从而为改进柱型、选择电色谱分离条件提供了理论参考。     

Mechanism of Charging of Au Atoms and Nanoclusters on Li Doped SiO2/Mo(112) Films

We present the results of supercell DFT calculations on the adsorption properties of Au atoms and small clusters (Au_n, n≤5) on a SiO₂/Mo(112) thin film and on the same system modified by doping with Li atoms. The adsorbed Li atoms penetrate into the pores of the silica film and become stabilized at the interface where they donate one electron to the Mo metal. As a consequence, the work function of the Li‐doped SiO₂/Mo(112) film is reduced and results in modified adsorption properties. In fact, while on the undoped SiO₂/Mo(112) film Au interacts only very weakly, on the Li‐doped surface Au atoms and clusters bind with significant bond strengths. The calculations show that this is due to the occurrence of an electron transfer from the SiO₂/Mo(112) interface to the adsorbed gold. The occurrence of the charge transfer is related to the work function of the support but also to the possibility for the silica film to undergo a strong polaronic distortion.     

同多酸和杂多酸修饰微电极的电化学研究 Ⅶ.磷钒钼杂多酸薄膜修饰微电极和杂多酸/聚苯胺薄膜修饰微电极的制备和电化学性质

本文详细描述了磷钒钼杂多酸（PV2Mo10）极薄膜修饰碳纤维（CF）微电极和PV2Mo10／聚苯胶（PAn）薄膜修饰微电极的制备及其电化学性质。     

Characterization of ultra smooth interfaces in Mo/Si-multilayers

The interface structure of Mo/Si-multilayers prepared by Pulsed Laser Deposition (PLD) on Si substrates at room temperature has been investigated. Already the in-situ ellipsometer data acquired during film growth indicate a particular behaviour of this material system that is caused by reaction/diffusion processes of the condensing atoms. MoSi(x) interlayers are formed both at the Mo on Si- and at the Si on Mo-interfaces. The results of multilayer characterization carried out by SNMS and RBS show similar concentration profiles for both types of the interlayers. More detailed information about interface structure and morphology can be provided by HREM investigations. In the TEM micrographs of various multilayers prepared for different laser light wavelengths an improvement of layer stack quality, i.e. formation of abrupt interfaces, with increasing photon energy is observed. Layer stacks having almost ideally smooth interfaces were synthesized by UV-photon ablation. HREM micrographs of these multilayers show a pronounced separation of spacer and absorber layers. The roughness sigma(R) of the interfaces between the amorphous Si- and MoSi(x)-layers was determined by image analysis. On the average a level sigma(R) approximately 0.1 nm is found. There is no indication for roughness replication or amplification from interface to interface as it is known from the appropriate products of conventional thin film technologies.     

Investigation on the photophysical processes in nanosized photocatalytic thin films using planar solid-state devices

The photophysical processes for three nanosized photocatalytic oxides, titanium dioxide (TiO₂) thin film, tin dioxide (SnO₂) thin film, and layered TiO₂/SnO₂ thin film, have been examined in planar solid-state devices. It is found that, for SnO₂ thin film, the dissociation of the photogenerated excitons can take place both on the film surface and inside the film, while for TiO₂ thin film, almost all excitons dissociate on the film surface. Such a difference is proposed to account for the higher photocatalytic activity of TiO₂ over SnO₂, since it is experimentally shown that the excitons dissociate in SnO₂ thin film as efficiently as they do in TiO₂ thin film. For layered TiO₂/SnO₂ thin film, when it is illuminated by a beam of UV light, it is suggested that there exists a local electrostatic field at the SnO₂ side of the interface, mainly formed by those holes efficiently photogenerated and then localized in SnO₂ thin film. The photo-induced local electrostatic field is believed to facilitate hole–electron separation on TiO₂ thin film and therefore increase the photocatalytic activity of the layered thin film over single TiO₂ thin film.     

Adsorption of nanoparticles at the solid-liquid interface

The adsorption of differently charged nanoparticles at liquid-solid interfaces was investigated by in situ X-ray reflectivity measurements. The layer formation of positively charged maghemite (γ-Fe(2)O(3)) nanoparticles at the aqueous solution-SiO(2) interface was observed while negatively charged gold nanoparticles show no adsorption at this interface. Thus, the electrostatic interaction between the particles and the charged surface was determined as the driving force for the adsorption process. The data analysis shows that a logarithmic particle size distribution describes the density profile of the thin adsorbed maghemite layer. The size distribution in the nanoparticle solution determined by small angle X-ray scattering shows an average particle size which is similar to that found for the adsorbed film. The formed magehemite film exhibits a rather high stability.     

Structural influence on Raman scattering of a new C60 thin film prepared by AAO template with the method of pressure difference

An anodic aluminum oxide (AAO) template is prepared by anodizing aluminum in oxalic acid solution. C60 crystals were grown, using the pressure difference method, in the pores of the template, representing a brushlike thin film layer with a honeycomb boundary structure in one side and nail arrays in the other side. Different Raman spectra of the C60 thin film from the both sides are presented, which indicate the different uniformly ordered structure character and the interface behavior of the C60 film on the surface with C60 crystals in the AAO nanopores. On the basis of energy and group theory, the strengthening of the Raman intensity and the broadening of Raman modes may imply that more transition spectral lines between vibration or rotation energy levels of C60 molecules were excited and detected.     

Determination of X-ray compression efficiency of a thin film X-ray waveguide structure using marker layer fluorescence

We demonstrate that a thin marker layer, sandwiched in the guiding medium of a thin film planner X-ray waveguide structure, can be used to determine X-ray compression efficiency for a particular excitation mode. It can also be used in evaluating the transmission efficiency of waveguide structure and for the determination of X-ray intensities reaching the waveguide exit. This approach has been applied for determining X-ray compression and transmission efficiency of a Mo/B₄C/Mo based X-ray waveguide structure, by inserting a thin Fe marker layer.     

Quantification of AES depth profiling data of polycrystalline Al films with Gaussian and non‐Gaussian surface height distributions

Sputtering‐induced roughness is the main distortional factor on the depth resolution of measured depth profiles, in particular, for sputtering of polycrystalline metals. Frequently, the surface height distribution of the sputtering‐induced roughness exhibits an asymmetrical feature. In such a case, a non‐Gaussian height distribution function (HDF) has to be applied for the quantification of a measured depth profile. By replacing the usually applied Gaussian HDF with that of an asymmetrical triangle in the Mixing‐Roughness‐Information depth model, measured Auger electron spectroscopy depth profiling data of the interface of polycrystalline Al films on Si are perfectly fitted. The asymmetric triangle height distributions obtained from the best fit are a reasonable approximation of the height distributions measured by atomic force microscopy. Copyright © 2013 John Wiley & Sons, Ltd.