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961.
The effect of lattice anharmonicity on the resonant modes of dilute impurities for Au-Cu, Au-Ag and W-Cr metallic systems
are studied from the poles of the double time temperature dependent impure Green’s function of these crystals. The third order
force constants used in the present work are derived assuming the systems to obey the Lennard-Jones potential. The inclusion
of lattice anharmonicity has been found to increase the resonant frequency which depends upon the mass defect, force constant
change parameter and the impurity concentration terms. Some interesting features about the phase shift and the change in width
of the vibrational spectrum are reported at room temperature for the isotopic defects and the defects interacting with host
atoms. The results are found to be in qualitative agreement with the experiments on the systems considered. 相似文献
962.
A new, fast and convenient method based on coupled thin-layer chromatography (TLC) and Fourier transform-infrared (FT-IR) microscopy is developed to separate, detect and identify the additives in polymers. After the TLC development, the analytes were transferred on to a barium fluoride (BaF2) salt plate via a special capillary technique and analysed by FT-IR microscopy. The additives used for stabilization of polypropylene and the plasticisers used for poly(vinyl chloride) were analysed as examples to illustrate this technique. The overall time taken for the experiment including transferring three marked spots and then identifying them was about 20 min. An amount as small as 0.5 μg can be easily detected and identified. It was a very convenient and reliable method to separate and evaluate complex additives for polymers without the interference from TLC adsorbent, because of a special transferring and identifying method, which is suitable to FT-IR microscopy. 相似文献
963.
964.
Michal Korenko Marián Kucharík Jozef Vincenc Oboňa Dušan Janičkovič Rosa Córdoba José María De Teresa Blanka Kubíková 《Helvetica chimica acta》2008,91(7):1389-1399
The rapid‐solidification processing (by a cooling rate of 105–106 K/s) was used for the preparation of deeply undercooled cryolite/alumina (Na3AlF6/Al2O3) melts. We found a mass of nanotubes on the surface of these undercooled melts. The nanotubes were preferentially located on the defect places of the surface with the following approximate dimensions: base≈100×100 nm, length≈1000 nm. The solidified samples with the nanotubes on the surface were analyzed by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), and infrared spectroscopy (IR). 相似文献
965.
再谈"三维导体"的自感系数 总被引:4,自引:1,他引:3
由公式ε=L│dI/dt│出发,只要求出“三维导体”中的等效自感电动势,即可求得自感系数L,并以无限长同轴电缆自感系数的求解为例加以证明。 相似文献
966.
电化学氢化物发生-原子荧光法测定环境样品中的Se(Ⅳ)和Se(Ⅵ) 总被引:1,自引:0,他引:1
设计了一种新的电化学氢化物发生装置, 用于测定不同价态的硒. 通过对传统的平板电解池的改进, 设计了全新的圆盘电解池并采用螺纹密封的方式, 极大地缩短了电解池的装配时间, 提高了电解池的使用寿命和密封性能. 结合热水浴在线还原技术, 将 Se(Ⅵ)在高浓度HCl介质中120 s内还原成Se(Ⅳ), 通过电化学氢化物发生技术生成氢化物, 成功的进行硒的在线价态分析. 对各种实验参数进行了详细的研究, Se(Ⅳ) 和Se(Ⅵ)的相对标准偏差分别为2.6% 和 3.1% (n=11);Se(Ⅳ)和总硒的检出限分别为0.32和0.27 μg/L (3σ). 相似文献
967.
在常利率环境下,研究当索赔时间间隔为Erlang(2)分布且保费收取为两步保费的风险模型,推导出该模型Gerber-Shiu罚金折现期望函数所满足的微积分方程. 相似文献
968.
A.M. Monakhov N.I. Sablina N.S. Averkiev C. elebi P.M. Koenraad 《Solid State Communications》2008,146(9-10):416-419
The influence of the host-crystal deformation on the acceptor wave-function in a cubic crystal is considered. The calculations are based on the numerical solution of the Luttinger Hamiltonian for a hole in a complex valence band. The deformation is taken into account using Bir-Pikus Hamiltonian for the deformation. The results can be used for the interpretation of the STM images in strained cubic crystals. 相似文献
969.
In this contribution, we highlight the state of the art in the determination of structures with ultrafast electrons and X‐rays. We provide our perspectives and reflections on the principles, techniques and methods, and on applications from different disciplines, with some focus on physical, chemical and biological structures. Although this article is not a survey of all the work done with these techniques, it provides a comprehensive referencing to current research. 相似文献
970.
测量了15~300K温度范围内57.5%Al1.5O-35%CaO-7.5%BaO玻璃中四价铬的发射光谱.这种材料中铬离子的能级处于Tanabe-Sugano图上弱场范围中,最低的激发态是3T2,发射谱是一个宽带.按照单频近似理论拟合低温下的光谱,得到3T2能级的零声子线位置Ezp=8400cm-1,声子能量tω=320cm-1,黄昆因子S=358.尽管单频近似能够较好地描述低温下的线形,发射光谱宽度随温度的变化却与单频近似理论的结果不符.讨论了这种差别的原因,认为可能的解释是与激发态耦合的声子能量大于与基态耦合的声子能量. 相似文献