Mechanical Behavior of Nanometer Ni by MD Simulation

The indention simulation of the crystal Ni is carried out by molecular dynamics technique (MD) to study the mechanical behavior at nanometer scales, the indenter tips with sphere shape is used. Some defects such as dislocations, point defects are observed. It is found that defects (dislocations, amorphous) nucleated is from local region near the pin tip or the sample surface. The temperature distribution of local region is analyzed and it can explain our MD simulation result.

Surface Plasmon Resonances of Cu Nanowire Arrays

Surface plasmon resonances of arrays of parallel copper nanowires, embedded in ion track-etched polycarbonate membranes, were investigated by systematic changes of nanowires’ topology and arrays area density. The extinction spectra exhibit two peaks which are attributed to interband transitions of Cu bulk metal and to a dipolar surface plasmon resonance, respectively. The resonances were investigated as a function of wire diameter and length, mean distance between adjacent wires, and angle of incidence of the light field with respect to the long wire axis. The dipolar peak shifts to larger wavelengths with increasing diameter and length, and diminishing mean distance between adjacent wires. Additionally, the shape effect on the dipolar peak is investigated.

云母模板中Cu纳米线的制备及其光学性质研究

Nanopores with diameters between 30 nm and 180 nm have been fabricated by inducing latent track with fast heavy ions and etching process in 25 μm thick,single-crystal muscovite mica.For short etching time,the nanopores are columns with circular cross section.For long etching time the cross section of nanopores becomes rhombic.Thus the shape of nanopores depends on the etching time.Cu nanowires have been fabricated with controlled dimensions by electrodeposition into the nanopores.The ultraviolet-visible lig...中文文摘：利用快重离子辐照的单晶白云母片产生潜径迹,蚀刻得到直径在30—180nm纳米孔道.孔道形状依赖于蚀刻时间,蚀刻时间短得到圆柱形孔道,蚀刻时间长得到菱柱形孔道.从而在云母模板孔道中电化学沉积得到不同直径和形状的Cu纳米线.通过紫外可见光谱分析,发现铜纳米线的尺寸和形状影响其光学性质.直径小于60nm的近似为圆柱状Cu纳米线有一个明显的表面等离子体共振峰和一个微弱的次峰.随着直径增加,菱柱状的Cu纳米线主峰有明显的红移,次峰逐渐增强.同时利用扫描电子显微镜、X射线衍射对Cu纳米线的形貌和晶体结构特征进行了表征.

Experimental study of the beta-delayed neutron decay of N-21

The first spectroscopic study for the beta decay of N-21 is carried out based on beta-n, beta-gamma, and beta-n-gamma coincidence measurements. The neutron-rich N-21 nuclei are produced by the fragmentation of the E/A=68.8 MeV Mg-26 primary beam on a thick Be-9 target and are implanted into a thin plastic scintillator that also plays the role of beta detector. The time of flight of the emitted neutrons following the beta decay are measured by the surrounding neutron sphere and neutron wall arrays. In addition, four clover germanium detectors are used to detect the beta-delayed gamma rays. Thirteen new beta-delayed neutron groups are observed with a total branching ratio of 90.5 +/- 4.2%. The half-life for the beta decay of N-21 is determined to be 82.9 +/- 7.5 ms. The level scheme of O-21 is deduced up to about 9 MeV excitation energy. The experimental results for the beta decay of N-21 are compared to the shell-model calculations.

Characteristics of a 4-fold segmented clover detectore

Four high-purity germanium 4-fold segmented Clover detectors have been applied in the experiment of neutron-rich nucleus N-21. The performance of those, four Clovers have been tested with radioactive sources and in-beam experiments and the main results including energy resolution, peak-to-total ratios, the variation of the hit pattern distribution in difficult crystals of one Clover detector with the energy of gamma ray, and absolute full energy peak detection efficiency curve, were presented.

Preparation and Optical Properties of Gold Nanowire Arrays

Gold nanowires with diameters (d) between,15 run and 200 urn and with length/diameter ratio of 700 were prepared in ion-track templates with electrode position method. The morphology and crystal structure of the gold nanowires were Studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The 200 nm (d) gold nanowires preferred orientation along the [100] direction were formed at the deposition voltage of 1.5 V (Without reference electrode). The optical properties of gold nanowire arrays embedded in ion-track templates were studied by UV-Vis spectrophotometer. There was a strong absorption peak at 539 nm for 45 nm (d) gold nanowire arrays. With the diameter of gold nanowires increasing, the absorption peak shifted to the longer wavelength. At last, the result was discussed combined with surface plasmon resonance of gold nanoparticles.

Preparation of Microporous Membranes by Swift Heavy Ion Irradiation and Impedance Characterization

Polypropylene (PP) microporous membranes were successfully prepared by swift heavy ion irradiation and track-etching. Polypropylene foils were irradiated with Au-197 ions of kinetic energy 11.4 MeV.u(-1) (total energy of 2245.8 MeV) and fluence 1x10(8) ions.cm(-2) at normal incidence. The damaged regions produced by the gold ions along the trajectories were etched in H2SO4 and K2Cr2O7 solutions leading to the formation of cylindrical pores in the membranes. The pore diameters of the PP microporous membranes increased from 380 to 1610 nm as the etching time increased from 5 to 30 min. The surface and cross-section morphologies of the porous membranes were characterized by scanning electron microscopy (SEM). The micropores in the membranes were found to be cylindrical in shape, homogeneous in distribution, and equal in size. Some mathematical relations of the porosity of the PP microporous membranes were established by analytic derivation. The microporous membranes were used in lithium-ion batteries to measure their properties as separators. The electrical conductivity of the porous membrane immersed in liquid electrolyte was found to be comparable to that of commercial separators by electrochemical impedance spectroscopy (EIS). The results showed that the porosity and electrical conductivity were dependent on the ion fluence and etching time. By adjusting these two factors, microporous membranes with good porosity and electrical conductivity were made that met the requirements for commercial use.

Field emission from TiO2/Ti nanotube arrays with different morphologies

Well-aligned TiO2/Ti nanotube arrays were electrochemically formed in a HF solution for different anodization times. Field emission scanning electron microscopy (FE-SEM) images reveal that anodization time had a great influence on the morphology of TiO2/Ti nanotube arrays. The composition of resulting nanotubes was analyzed by X-ray photoelectron spectroscopy (XPS). Field emission properties of the prepared samples with different morphologies were investigated by the Fowler-Nordheim (F-N) theory. The results indicate that the morphology can affect field emission behaviors. TiO2/Ti nanotube arrays with clear, uniform, and short nanotubes display moderate field emission properties, and have the better turn-on field of 4.6 V/mu m and good field emission stability. (C) 2010 Elsevier B.V. All rights reserved.

Investigation of add-back effects in a segmented Clover detector

The resolution and the summing characteristics of an EXOGAM segmented Clover germanium detector has been studied for use it in gamma spectroscopic experiments. The measurements have been performed with standard radioactive sources of Eu-152, Ba-133 and beta-delayed gamma-rays from Ir-176 decay. The data analytic results, realized by software, are presented in this paper.

基于重离子径迹模板法的纳米线制备与性能研究

本文从纳米材料概念及特性分析入手，介绍了当前纳米线制备方法及其应用，重点对基于重离子径迹模板法的纳米线制备与性能研究进行阐述，本文具体研究内容包括以下几个方面：利用电化学沉积法在重离子径迹模板中制备出直径从30到500 nm、包括单晶和多晶结构的银纳米线阵列，实验结果表明所制备的银单晶纳米线沿(111)面择优取向生长；直径为100 nm的银纳米线在温度低于50 K时，电阻急骤减小。不同直径金纳米线利用电化学沉积法在重离子径迹模板中成功制备，利用XRD测得所制备金纳米线沿(200)面择优取向生长。对金纳米线阵列紫外吸收光谱研究表明，吸收光谱峰位随直径的增加向长波方向移动，同时半高宽增加。当入射光与金纳米线有一定夹角时，其吸收峰随着夹角的增加向短波方向移动。另外，金纳米线在空气中的氧化现象通过其紫外吸收光谱被间接观察到。利用电化学共沉积技术在重离子径迹模板中成功制备出InSb半导体纳米线，通过实验证明，InSb半导体纳米线共沉积电位位于-1.3-1.4 V之间。通过对Cu/Co多层纳米线研究发现，所制备出的Cu/Co多层纳米线具有好的柔韧性，不容易在层间发生断裂

利用重离子径迹模板制备纳米线/纳米管及其光学性质测量

本论文主要研究内容包括重离子径迹模板的制备，一维纳米材料包括半导体CdS纳米线/管和金属Cu纳米线的制备，以及纳米线/管的光学性质测量三个部分。利用高能重离子辐照、蚀刻技术，制备了不同孔径的聚碳酸酯和白云母两种模板。聚碳酸酯模板的孔道形状为圆柱形。云母模板的孔道形状与蚀刻时间有关，短时间蚀刻为圆形，长时间蚀刻为菱形。利用聚碳酸酯模板结合电化学的方法可控制备了CdS纳米线和纳米管。纳米线和纳米管的直径在20至110 nm，长度在十几个微米。X射线衍射和选区电子衍射表明所制备的CdS纳米线和纳米管为多晶结构。通过对嵌有CdS纳米线和纳米管的聚碳酸酯模板的紫外可见光谱分析，发现随着纳米线和纳米管尺寸减小，吸收峰明显蓝移。实验中同时发现，制备的CdS纳米线是由纳米管通过填充生长机制产生的。利用白云母模板结合电化学方法可控制备了金属Cu纳米线。Cu纳米线的形状由模板孔道的形状决定。通过嵌有Cu纳米线的云母模板的紫外可见光谱分析，发现直径小于60 nm的Cu纳米线有一个强的共振峰和一个微弱的次峰。随着纳米线直径增加，吸收峰发生明显的红移，同时次峰增强。结果表明，Cu纳米线直径和形状可以改变电子的共振模式，从而引起纳米线光吸收的改变

Controllable synthesis of metal hydroxide and oxide nanostructures by ionic liquids assisted electrochemical corrosion method

Cu(OH)(2) nanowires have been synthesized by anodic oxidation of copper through a simple electrolysis process employing ionic liquid as an electrolyte. Controlling the electrochemical conditions can qualitatively modulate the lengths, amounts, and shapes of Cu(OH)(2) nanostructures. A rational mechanism based on coordination self-assembly and oriented attachment is proposed for the selective formation of the polycrystalline Cu(OH)(2) nanowires. In addition, the FeOOH nanoribbons, Ni(OH)(2) nanosheets, and ZnO nanospheres were also synthesized by this route, indicative of the universality of the electrochemical route presented herein. The morphologies and structures of the synthesized nanostructures have been characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD). Fourier transform infrared spectra (FT-IR), and thermogravimetric (TG). (C) 2007 Elsevier Masson SAS. All rights reserved

Hyperbranched polymer-assisted hydrothermal in situ synthesis of submicrometer silver tubes

We produced silver tubes with an outer diameter of 1 mu m, wall thickness of 200 nm, and length of hundreds of micrometers by hydrothermal treatment of aqueous solutions of AgNO3 and hyperbranched polyglycidol (HPG) at 165 degrees C. The surfaces of the silver tubes were chemically modified by HPG, which was confirmed by FTIR of the silver tubes.