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51.
肼在金属表面上分解机理的理论研究 总被引:1,自引:0,他引:1
键指数归一-二次指数势(Unity Bond Index-Quadratic Exponential Potential, UBI-QEP)法被用于研究肼在Fe, Ru, Pt和Cu表面上的分解机理. 研究结果表明, 肼在金属上优先发生N—N键断裂, 金属活性顺序是Ru~Fe>Pt>Cu, 但不同金属上呈现出不同的产物选择性. 在Fe, Ru上产物主要为N2和H2, 其通过N2Hx物种形成的可能性较低, 金属活性顺序为Ru>Fe; 而在Cu, Pt上最终产物为NH3, N2和H2, 其中H2和N2的形成可能部分源于中间体物种N2H的转化, 金属的活性顺序为Pt>Cu. 相似文献
52.
LI Yi ;NI Bi-Lian ;HU Jian-Ming ;ZHANG Yong-Fan ;CHEN Wen-Kai ;LI Jun-Qian 《结构化学》2008,27(8):1002-1008
The adsorption of cyanide on the top site of a series of transition metal M(100) (M = Cu, Ag, Au, Ni, Pd, Pt) surfaces via carbon and nitrogen atoms respectively, with the CN axis perpendicular to the surface, has been studied by means of density functional theory and cluster model. Geometry, adsorption energy and vibrational frequencies have been determined, and the present calculations show that the adsorption of CN through C-end on metal surface is more favorable than that via N-end for the same surface. The vibrational frequencies of CN for C-down configuration on surface are blue-shifted with respect to the free CN, which is contrary to the change of vibrational frequencies when CN is adsorbed by N-down structure. Furthermore, the charge transfer from surface to CN causes the increase of surface work function. 相似文献
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Study on the Reaction Mechanism for Carbon Dioxide Reforming of Methane over supported Nickel Catalyst 总被引:1,自引:0,他引:1
LingOIAN ZiFengYAN 《中国化学快报》2003,14(10):1081-1084
The adsorption and dissociation of methane and carbon dioxide for reforming on nickel catalyst were extensively investigated by TPSR and TPD experiments. It showed that the decomposition of methane results in the formation of at least three kinds of surface carbon species on supported nickel catalyst, while CO2 adsorbed on the catalyst weakly and only existed in one kind of adsorption state. Then the mechanism of interaction between the species dissociated from CH4 and CO2 during reforming was proposed. 相似文献
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提出并分析了一种结构紧凑的截线型滤波器。该滤波器建立在一种硅基混合型表面等离激元波导结构上。与通常的混合等离激元结构相比,该波导结构在制作时只需对顶部的一层硅材料进行刻蚀,不需在光刻步骤进行对准和套刻,工艺简单易行。该截线滤波器由一截突柱波导与直波导耦合组成,并采用三维时域有限差分方法对其频谱响应进行模拟计算。计算结果表明该滤波器与现有文献中的二维金属-绝缘体-金属波导截线滤波器具有类似的频谱特性。另外,还进一步分析了截线部分及波导自身尺寸对器件输出频谱的影响。 相似文献
57.
Self-Organized Micro-Columns and Nano-Spheres Generated by Pulsed Laser Ablation of Ti/A1 Alloy in Water 下载免费PDF全文
Dense arrays of micro-columns are formed on the surface of Ti-AI alloy by cumulative nanosecond pulsed laser ablation in water. The fabric-like structure characterized by Ti-A1 nano-spheres absorbed on micro-duster in liquid is most likely responsible for the occurrence of laser micro-etching and localized melting, resulting in continuous deepening of micro-holes and the formation of micro-columns. Laser induced plasma spectroscopy is carried out to reveal the effect of micro-columns on subsequent pulse laser ablation. The intensity of spectral lines from Ti ions by additional laser ablation of the modified spot is higher than that created over a smooth surface. These results suggest that the micro-columns lead to an enhanced absorption of the following laser energy. The proposed results and relevant discussions are of importance for the development of light-trapping coatings on a metal surface. 相似文献
58.
From self-assembly to quantum guiding: A review of magnetic atomic structures on noble metal surfaces 下载免费PDF全文
Recent advances in the study of magnetic atomic structures on noble metal surfaces are reviewed. These include one- dimensional strings, two-dimensional hexagonal superlattices, and novel structures stabilized by quantum guiding. The combined techniques of low-temperature scanning tunneling microscopy, kinetic Monte Carlo simulations, and ab initio calculations reveal that surface-state-mediated adatom-step and adatom-adatom interactions are the driving forces for self- assembly of these structures. The formation conditions are further discussed by comparing various experimental systems and the kinetic Monte Carlo simulations. Using scanning tunneling spectroscopy and tight-binding calculations together, we reveal that the spectra of these well-ordered structures have characteristic peaks induced by electronic scattering processes of the atoms within the local environment. Moreover, it is demonstrated that quantum confinement by means of nano-size corrals has significant influence on adatom diffusion and self-assembly, leading to a quantum-guided self-assembly. 相似文献
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Reliable Lateral Manipulation of Single Adatom on Metal fcc(lll) Surfaces with a Single-Atom Tip 下载免费PDF全文
Using molecular statistics simulations based on the embedded atom method potential, we investigate the reliability of the lateral manipulation of single Pt adatom on Pt(111) surface with a single-atom tip for different tip heights (tip-surface distance) and tip orientations. In the higher tip-height range, tip orientation has little influence on the reliability of the manipulation, and there is an optimal manipulation reliability in this range. In the lower tip- height range the reliability is sensitive to the tip orientation, suggesting that we can obtain a better manipulation reliability with a proper tip orientation. These results can also be extended to the lateral manipulation of Pd adatom on P d (111) surface. 相似文献