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871.
We investigate the exact solution of the Dirac equation for the Mie-type potentials under the conditions of pseudospin and spin symmetry limits. The bound state energy equations and the corresponding two-component spinor wave functions of the Dirac particles for the Mie-type potentials with pseudospin and spin symmetry are obtained. We use the asymptotic iteration method in the calculations. Closed forms of the energy eigenvalues are obtained for any spin-orbit coupling term κ. We also investigate the energy eigenvalues of the Dirac particles for the well-known Kratzer-Fues and modified Kratzer potentials which are Mie-type potentials. 相似文献
872.
873.
S.J. Pestehe G.J. Tallents 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,72(6):853-878
A method of parameterizing escape factors (transmission factors and net radiative brackets) for conditions typical of laser-produced plasmas is introduced. The assumptions of planar geometry, exponentially decreasing emissivity and absorption coefficient with distance with a step rise at a particular point, and spatially constant Doppler broadened line profiles have been made. The effect of velocity gradients in spectrally shifting the absorption and emission line profiles relative to each other is taken into account assuming linear velocity gradients with distance. A parameter R representing the ratio of the spatial scale-length of the absorption coefficient to the Doppler decoupling length is introduced. Fitting formulae for transmission factors and net radiative brackets are given which are valid for all R and all optical depths. In the limit of small R (large Doppler decoupling length), the escape factors asymptotically approach formulae developed originally by, for example, Holstein assuming negligible plasma velocities. For large R (small Doppler decoupling length), the escape factors have been shown to asymptotically approach the Sobolev approximation. The parameterized net radiative bracket has been used in the hydrodynamic and atomic physics code ‘EHYBRID’ for the calculation of the effect of radiation trapping on population densities in laser-produced plasmas. The output of the modified EHYBRID code has then been post processed using the parameterised transmission factors to simulate 123 Ne-like and 399 F-like germanium resonance line intensities emitted in typical X-ray laser experiments. We obtain an agreement between the simulated and experimental spectra. 相似文献
874.
K. Knoche L. Sprute W. Behrmann E. Mordhorst W. Scobel M. Strecker B. Cramer B. Gebauer D. Hilscher U. Jahnke E. Schwinn 《Zeitschrift für Physik A Hadrons and Nuclei》1992,342(3):319-327
Energy spectra and multiplicities of neutrons from the reaction system 838 MeV32S projectiles on197Au have been measured in coincidence with binary fragmentations. Neutron detection was performed simultaneously in a 4 scintillator sphere and by time-of-flight. The linear momentum transfer (LMT) and the excitation energyE
CN
*
are deduced with the folding angle technique. Neutron multiplicities are compared for consistency and discussed as a measure of LMT andE
CN
*
. The saturation ofM
4
(E
CN
*
) beyondE
CN
*
400 MeV seen for several systems of high fissility (x0.8) is attributed to the spreading of the folding angle distribution and the increasing competition of charged particle evaporation. 相似文献
875.
分别以硅-二氧化硅和锗-二氧化硅复合靶作为溅射靶,采用磁控溅射技术在p型硅衬底上淀积了含纳米硅的氧化硅薄膜和含纳米锗的氧化硅薄膜.各样品分别在氮气氛中经过300至1100℃不同温度的退火处理.使用高分辨透射电子显微镜可以观察到经900和1100℃退火的含纳米硅的氧化硅薄膜中的纳米硅粒,和经900和1100℃退火的含纳米锗的氧化硅薄膜中的纳米锗粒.经过不同温度退火处理的含纳米硅的氧化硅和含纳米锗的氧化硅薄膜的光致发光谱均具有相似的峰型,且它们的发光峰位均位于580nm(2.1eV)附近.可以认为含纳米硅的氧化硅和含纳米锗的氧化硅薄膜的光发射主要来自于SiO2层中发光中心上的复合发光,对实验结果进行了合理的解释 相似文献
876.
U. Müller-Herold 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(3):311-315
Angular correlation in three-body systems varies between the limiting cases of slightly perturbed equi-distribution, as in
the electronic ground state of helium and directed bond-type bent structure, as in the isolated water molecule. In an exactly
solvable modification of the Hooke-Calogero model, it is shown that there is a sharp transition between the two cases if the
particles’ masses are suitably varied. In the Hooke-Calogero model attraction between different particles is harmonic and
the repulsion between equal particles is given by a 1/r
2 potential. The bent structure appears in the angular distribution function if the masses of the two equal particles are below
a critical value, which depends on the mass of the third particle. Above the critical value, the angular correlation is of
helium type and exhibits a minimum at 0° corresponding to the Coulomb hole and a maximum at 180°. The model thus demonstrates
the modulating role of mass in the transition between semi-rigid structure and more diffuse nuclear states. 相似文献
877.
878.
The correspondence between ordinary differential equations and Bethe ansatz equations for integrable lattice models in their continuum limits is generalised to vertex models related to classical simple Lie algebras. New families of pseudo-differential equations are proposed, and a link between specific generalised eigenvalue problems for these equations and the Bethe ansatz is deduced. The pseudo-differential operators resemble in form the Miura-transformed Lax operators studied in work on generalised KdV equations, classical W-algebras and, more recently, in the context of the geometric Langlands correspondence. Negative-dimension and boundary-condition dualities are also observed. 相似文献
879.
Chengzhao Chen Linghong LiaoCheng Li Hongkai LaiSongyan Chen 《Applied Surface Science》2011,257(7):2818-2821
High-quality strain relaxed SiGe layer has been fabricated on Si using a thin Ge interlayer grown at 330 °C. The properties of SiGe layers with and without the low-temperature Ge interlayer are compared. The results indicate that the Ge interlayer plays an important role in the preparation of SiGe layer. The strain relaxed low-temperature Ge interlayer with coalesced island surface, acting as a stable and compliant template, could remove the cross-hatch misfit dislocation lines on surface and promote the strain relaxation in the SiGe layer homogeneously. 相似文献
880.
基于BGO晶体的反射型法拉第光纤电流传感器 总被引:1,自引:1,他引:1
采用Bi4Ge3O12(BGO)晶体作为传感元件,设计了一种闭合磁环型光纤电流传感器,并对其传感特性进行了理论分析和实验研究.将BGO晶体加工成一带斜面的长方体,并在端面镀金属膜,通过光在晶体中多次临界反射来增大光程以提高测量灵敏度.实验测量得到的法拉第转角与采用倍频法测量的结果符合较好,但与实际结果存在一较大比例系数.对产生该系统误差的主要因素——传感头端面金属膜反射引起的相移及入射角偏离临界角时产生的相移进行了详细地理论分析和数值模拟.结果表明,金属膜反射和偏离临界角引起的相移对测量结果均有较大影响,但输出与作用在传感头上的磁感应强度呈很好的线性关系,可以通过将传感器的测量值乘上一个补偿系数来消除反射相移所产生的误差. 相似文献