共查询到20条相似文献,搜索用时 18 毫秒
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R. D. Mathad H. G. Harish Kumar B. Sannakki S. Ganesh K. S.S. Sarma M. V. Badiger 《辐射效应与固体损伤》2013,168(10):656-664
The effect of an 8 MeV electron-beam on the structural, optical and dielectric properties of polystyrene films has been investigated respectively by means of Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–VIS) spectroscopy and electrical impedance (LCR) analysis over a radiation dose in the range of 50–250 kGy using a Microtron accelerator. The FTIR spectral analysis shows no change in the overall structure of the irradiated polystyrene films, except a minor change in the intensity of a few peaks in the FTIR spectrum, indicating that polystyrene is resistant to electron-beam irradiation over the range of radiation doses investigated. The optical band gap analysis using the UV–VIS absorption spectra of the polystyrene shows a small decrease in the optical band gap (E g) and the activation energy with an increase in electron doses. Further, the dielectric measurements over a frequency range of 100 Hz to 1 MHz for the electron-beam-irradiated polystyrene films show that both the dielectric constant and the dielectric loss increase with an increase in electron radiation dose, which may be ascribed to the formation of defect sites in the band gap of polystyrene as a consequence of molecular chain scission in the polymer films upon irradiation. 相似文献
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Pure gold is electron irradiated with 2.8 MeV electrons at 450±50°C. Both electrical resistivity and transmission electron microscopy showed damage which anneals at about 800°C. 相似文献
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The study of the electron structure of Ag, Au and Cu transition metals by EELS shows that the greatest electron concentration in conduction band observes in Ag and decreases through Au to Cu. At the same time the fraction of free-electron in conduction band of Ag is less than 0.2 while this value is about of 0.5 for Au and more than 0.6 for Cu. Thus the electron system of these elements consists from high-energy free-electron and low-energy nearly free-electron subsystems. The SFE of Ag, Au and Cu increases with increasing free-electron fraction in electron system of these metals. The explanation of this phenomenon was discussed in the frame of electron theory of metals. 相似文献
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根据原电子射程表达式和金属的有效真二次电子发射系数表达式,推导出金属的高能有效真二次电子发射系数与入射能量、能量幂次的关系式;并根据金属的高能有效真二次电子发射系数与金属的高能二次电子发射系数的关系,推导出金属的高能二次电子发射系数与入射能量、能量幂次的关系式。用实验数据计算出高能原电子轰击在金或银上时原电子入射能量幂次n,采用实验数据证实高能二次电子发射系数与原电子入射能量和能量幂次三者的关系,对结果进行讨论并得出结论:当高能原电子轰击在同一块金属上时,高能二次电子发射系数与原电子入射能量的n-1次幂之积近似为一常数。 相似文献
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根据原电子射程表达式和金属的有效真二次电子发射系数表达式,推导出金属的高能有效真二次电子发射系数与入射能量、能量幂次的关系式;并根据金属的高能有效真二次电子发射系数与金属的高能二次电子发射系数的关系,推导出金属的高能二次电子发射系数与入射能量、能量幂次的关系式。用实验数据计算出高能原电子轰击在金或银上时原电子入射能量幂次n,采用实验数据证实高能二次电子发射系数与原电子入射能量和能量幂次三者的关系,对结果进行讨论并得出结论:当高能原电子轰击在同一块金属上时,高能二次电子发射系数与原电子入射能量的n-1次幂之积近似为一常数。 相似文献
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An endogenous reconnection process involves a driving factor that lays inside the layer where a drastic change of magnetic field topology occurs. A process of this kind is shown to take place when an electron temperature gradient is present in a magnetically confined plasma and the evolving electron temperature fluctuations are anisotropic. The width of the reconnecting layer remains significant even when large macroscopic distances are considered. In view of the fact that there are plasmas in the Universe with considerable electron thermal energy contents this feature can be relied upon in order to produce generation or conversion of magnetic energy, high energy particle populations and momentum and angular momentum transport. 相似文献
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The differential cross-sections forē-helium elastic scattering are calculated by using Yateshigh-energy higher order Born approximations, through 0 (K
i
Emphasis>−2
) of the incident electron momentum, and comparisons have been made with the recent theoretical and experimental results. 相似文献
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基于高入射能量电子产生二次电子发射的物理过程, 分别对高入射能量电子产生的真二次电子和背散射电子的概率进行理论分析与建模. 利用Bethe能量损失模型和内二次电子逸出概率分布, 推导出高入射能量电子产生有效真二次电子发射的系数与入射能量的关系式; 根据高入射能量电子在材料内部被吸收的规律, 推导出高入射能量电子产生背散射电子的系数与入射能量之间的关系式. 结合两者得到高入射能量下金属的二次电子发射模型. 利用该模型计算得到典型金属材料Au, Ag, Cu, Al的二次电子发射系数, 理论计算结果与采用Casino软件模拟金属内部散射过程得到的数值模拟结果相符.
关键词:
二次电子发射
高入射能量
金属表面
散射过程 相似文献
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In this work, optimized size distribution and optical properties in the colloidal synthesis of gold nanoparticles (GNPs) were obtained using a proposed ultrasonic irradiation assisted Turkevich-Frens method. The effect of three nominal ultrasound (20 kHz) irradiation powers: 60, 150, and 210 W have been analyzed as size and shape control parameters. The GNPs colloidal solutions were obtained from chloroauric acid (HAuCl4) and trisodium citrate (C6H5Na3O7·2H2O) under continuous irradiation for 1 h without any additional heat or stirring. The surface plasmon resonance (SPR) was monitored in the UV–Vis spectra every 10 min to found the optimal time for localized SPR wavelength (), and the 210 sample procedure has reduced the localization at 20 min, while 150 and 60 samples have showed at 60 min. The nucleation and growth of GNPs showed changes in shape and size distribution associated with physical (cavitation, temperature) and chemical (radical generation, pH) conditions in the aqueous solution. The results showed quasi-spherical GNPs as pentakis dodecahedron ( = 560 nm), triakis icosahedron ( = 535 nm), and tetrakis hexahedron ( = 525 nm) in a size range from 12 to 16 nm. Chemical effects of ultrasound irradiation were suggested in the disproportionation process, electrons of AuCl2− are rapidly exchanged through the gold surface. After AuCl4− and Cl− were desorbed, a tetrachloroaurate complex was recycled for the two-electron reduction by citrate, aurophilic interaction between complexes AuCl2−, electrons exchange, and gold seeds, the deposition of new gold atoms on the surface promoting the growth of GNPs. These mechanisms are enhanced by the effects of ultrasound, such as cavitation and transmitted energy into the solution. These results show that the plasmonic response from the reported GNPs can be tuned using a simple methodology with minimum infrastructure requirements. Moreover, the production method could be easily scalable to meet industrial manufacturing needs. 相似文献
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A magnetic-free high resolution parabolic mirror time-of-flight electron energy spectrometer 总被引:1,自引:0,他引:1
XIA Yuanqin CHEN Deying WU Xiaoyan LU Xingfa YAO Qin Wang Qi 《Chinese Journal of Lasers》2001,10(2):93-96
1 Introduction Theresearchontheelectronresidualenergyofionizationofatomsandmoleculesintheintenselaserfieldhasnotonlysignificancefortestingandimprovingthecurrenttheoryofionizationbutalsowideapplicationforeground .Sopeopleaffordmuchontheresearchoftheor… 相似文献
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Daniel Aronov 《Surface science》2007,601(21):5042-5049
We observe a pronounced variation of wettability properties in solid state materials induced by a low-energy electron beam. The phenomenon occurs in several stages characterized by various mechanisms. We show that for low electron doses the irradiation leads to decrease in the wetting of a dielectric surface due to induced surface electric potential. The higher electron charge leads to formation of a chemical monolayer on material’s surface. It has been found that the electron irradiation strongly modifies the surface free energy of SiO2 by decreasing its total surface free energy value, almost twice. However, electron-induced variations of dispersive and polar components of the surface free energy are quite different and depend of incident electron charge. 相似文献
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《Radiation measurements》1995,25(1-4):251-256
Basic data are presented on the parameters of fragmentation, multiplicities and angular spectra of low energetic targed associated particles in the interction of 197Au nuclei of 10.7A GeV. 相似文献
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根据陶瓷介质材料具有高介电常数和高工作场强的特性,从理论上分析了陶瓷电容器具有的储能密度高、可工作在数kHz至数MHz的振荡放电回路中和老化缓慢等特性。对试制的1μF/500V的多层陶瓷电容器(MLC)试样品进行了750V 的1min直流耐压和100Hz重复充放电等可靠性试验研究,结果表明:该MLC在500V工作电压下(对应的体积储能密度达到720J/L)重复充放电寿命达107次以上;50kHz振荡放电输出电流峰值达320A;试验前后电气性能保持不变。因此,这种陶瓷电容器适合用作强脉冲大功率电源的储能元件。 相似文献
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The three photons from the dominant ortho-positronium decay and two vector mesons from the ηc exclusive decays are found to be in tripartite and high-dimensional entangled states, respectively. These two classes of entangled states possess the Hardy type nonlocality and allow a priori for quantum mechanics vs local realism test via Bell inequalities. The experimental realizations are shown to be feasible, and a concrete scheme to fulfill the test in experiment via two-vector-meson entangled state is proposed. 相似文献