共查询到19条相似文献,搜索用时 78 毫秒
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电子原子散射中的S,T,U参数可用来描述散射前后自旋状态的变化,研究精细结构水平上的散射激发振幅之间的关系,进而揭示电子原子碰撞过程中电子自旋-轨道耦合以及电子-电子交换等自旋相关效应.采用扭曲波玻恩近似计算了钠原子受电子散射S→P跃迁中的S,T,U参数,分析了多种入射能(2.2—60 eV)的电子与钠原子激发S→P跃迁过程的S,T,U参数随散射角的分布,其中对10 eV入射能的Sp参数与已报道实验数据符合一致.结果表明,较低能电子入射下的S,T,U参数随散射角的分布幅度和起伏都比较明显,入射能大于40 eV的电子入射,S,T,U参数的散射角分布变化很小.
关键词:
散射激发
S')" href="#">S
T')" href="#">T
U参数')" href="#">U参数
散射振幅
自旋相关效应 相似文献
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电子被氩,氪,氙原子散射总截面的光学模型研究 总被引:1,自引:0,他引:1
文中基于光学模型势方法,详细分析并改进了一种准自由模型吸收势,把它作为光学模型的虚部,在能量0.1-300eV的范围内计算了电子被Ar,Kr,Xe原子散射的总截面,计算结果与实验值进行了比较。 相似文献
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本文根据电磁场矢量球波函数多极点展开原理及矢量叠加定理提出了递归T矩阵算法的矢量形式,并且基于矢量递归T矩阵算法建立了多散射球模拟离散随机散射体散射的三维电磁散射模型.通过计算不同尺寸、随机分布散射球的散射以及分析散射球间的高阶散射效应,结果表明:矢量递归T矩阵算法具有很高的计算精度,算法中包含多散射体间的高阶散射效应,因此能够精确计算多散射体总的散射效应.本文所建模型可应用于土壤湿度探测工程中评估地表下掩埋离散随机散射体散射对雷达回波信号产生的影响. 相似文献
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本文对本研究组主要的研究领域——利用中子散射研究铁基超导体系Fe1+yTe1-xSex中磁性与超导的相互作用进行简要综述. Fe1+yTe1-xSex具有和其他铁基、铜基超导体相似的相图——母相Fe1+yTe是反铁磁体, 随着Se掺杂的增加, 母相的反铁磁序受到抑制, 随后在x~30%处体超导出现, 在x~50%处达到最佳掺杂, 此时超导转变温度Tc~ 15 K, 达到整个体系在常压下的Tc最大值. 它们的相图又存在着差别: 在相图末端, 即当Se掺杂达100%时, Fe1+ySe 仍然超导, Tc~8 K. 该体系母相磁有序的面内波矢大致为(0.5,0) (采用每个原胞含2个铁原子的四方结构), 随着Se含量的增加, 在超导逐渐发展的同时, 磁激发谱的谱重被逐渐转移到波矢为(0.5,0.5) 处. (0.5,0.5) 处在温度低于Tc 时出现中子-自旋共振峰. 施加外磁场后, 超导受到抑制, 该共振峰也被压制. 从这些实验结果我们得到以下的结论: 在这个体系中磁性和超导紧密耦合在一起——(0.5,0) 处的静态磁有序与超导互相竞争, (0.5,0.5) 附近的自旋激发则可能对超导电性的形成具有重要的促进作用. 本文还将简要讨论磁性的来源和3d 过渡金属的替代效应. 相似文献
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原子碰撞中的取向(orientation)参数的研究为原子碰撞动力学、原子受激态结构提供了丰富的信息.散射靶原子集合可用态多极(state multipole)描述,用它可以表征受激态原子的取向参数.通过取向参数与受激原子态退激的偶极辐射光子的Stokes参数之间的关系,可以进行实验与理论的比较.本文主要研究钠原子受电子散射S→P跃迁中取向参数,根据散射理论的扭曲波近似展开计算得到的散射振幅,带入态多极,然后计算钠原子3P态取向与散射角的关系及不同入射能下受激态取向参数变化特点,并与电子-光子符合散射实验所测数据进行比较.考虑到符合散射实验的测量困难,在误差范围内,理论分析与实验结果符合得比较好.
关键词:
取向参数
态多极
Stokes参数
电子-光子符合测量 相似文献
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针对激光散射法测量0.1 m~10 m微小球形颗粒过程中,Mie散射理论各参数的分析、计算、最优化选取比较复杂和繁琐,通过收敛速度、折射率和尺度参数测量范围、叠加次数的比较,采用球形粒子Mie散射参量的MATLAB改进算法, 结合MATLAB较强的计算能力和LabVIEW良好的图形化界面,进行LabVIEW和MATLAB混合编程。设计了Mie散射理论参数分析系统,系统实现散射系数的计算,并分别对散射系数与颗粒直径关系曲线、散射强度分布曲线、入射光波长与散射光强关系曲线、颗粒直径与散射光强关系曲线、入射光偏振角与散射光强关系曲线进行分析。通过实验结果和结论对比验证系统可行,且散射系数、消光系数和散射光强的计算结果可精确到小数点后17位,从而达到减少大量计算和编程工作的目的。 相似文献
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V. S. Igropulo 《Russian Physics Journal》1972,15(10):1443-1446
A calculation (accurate up to terms in 2) is performed of quasiclassical phase shifts and of differential and total cross sections of elastic electron scattering by a xenon atom in the static field approximation, with and without exchange.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 69–73, October, 1972.The author is grateful to N. I. Zhirinov, under whose guidance this work was performed. 相似文献
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Aleksander Jablonski 《Physica A》1985,129(3):591-600
The parameters describing scattering of electrons by atoms, which usually involve multiple integration of the atomic potentials, may be severely affected by the accuracy of these potentials. In the present work an iterative procedure is proposed providing a sequence of solutions of the Thomas-Fermi equation with increasing accuracy. Such a sequence makes it possible to establish the sensitivity of a given parameter to the accuracy of the atomic potential, and consequently to determine the accurate value of this parameter. Based on the present solutions, the differential scattering cross-sections for the Thomas-Fermi atom are calculated, and are found to deviate from the literature data. 相似文献
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The recent progress in the production of highly monochromatic atomic beams is opening new perspectives in surface physics, having paved the way for a full determination of the surface vibrational structure. After a discussion on the possible determination of Rayleigh wave dispersion curves from angular distributions exploiting the kinematical focussing effect, a short review is presented on the direct measurement of surface phonon dispersion curves, first achieved by Brusdeylins, Doak and Toennies in alkali halides, from time-of-flight (TOF) spectra of scattered He atoms. A comparison is made with the existing theories of surface phonons in ionic crystals. The state of the art in the theory of inelastic processes is briefly illustrated in order to discuss the theoretical interpretation of TOF spectra. The one-phonon energy loss spectra of He scattering from LiF(001) calculated for a hard corrugated surface model are found to be in general good agreement with the experimental TOF spectra. From such a comparison evidence is obtained that: i) one-phonon processes are predominant, and ii) in addition to Rayleigh waves important contributions to the inelastic scattering come from the surface-projected density of bulk phonons. Important effects due to inelastic resonances with surface bound states are put in evidence and explained by simple kinematical arguments. The possible observation of surface optical modes in NaF(001) is finally discussed. 相似文献
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The second-order Born-approximation treatment of Cutler and Schucan was applied to inelastic electron scattering data on 6Li, 60Ni, and 114Cd acquired at low momentum transfers. The form factors as a function of momentum transfer q in the range of 0.25–0.57 fm?1 were obtained by angular distribution measurements performed at incident energies of 30 to 60 MeV. The correlation between two parameters deduced from the measurements, the reduced transition probability B(E2↑) and the transition radius R(2)tr, is discussed. It is suggested that inelastic electron scattering data at low-q is best used either in conjunction with an accurate value of B(EL↑) (available from the model-independent analysis of “photon” experiments at zero momentum transfer) to allow accurate determination of R(2)tr, or in conjunction with high-q inelastic electron scattering data to allow accurate determination of B(EL↑) as well as R(2)tr. 相似文献
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在原子法激光同位素分离工程中,电子枪加热金属铀产生的原子蒸气的密度、速度以及温度等宏观量分布特性是非常重要的参数.为了分析电子枪功率和束宽对原子蒸气密度、速度、温度、质量通量和速度分布等物理特性的影响,采用直接MonteCarlo方法用柱坐标模拟了铀原子平面蒸发动力学过程.在电子枪加热方式下,蒸发源温度场不均匀,而且温度场随电子枪功率和束宽变化.着重研究这种变化对蒸气各种物理特性的影响.模拟结果表明,电子枪功率越高,蒸气径向宏观漂移速度越大,蒸发量越大;电子束束宽越窄,蒸发量越大.
关键词:
金属蒸发
原子法激光同位素分离
直接MonteCarlo
电子枪 相似文献
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《Physics letters. A》1996,222(6):405-408
Elastic scattering of electrons from sodium clusters (Na8, Na20) is investigated for impact energies below the inelastic threshold of about 1 eV. We show that the observed resonance structure of the elastic cross section strongly depends on the inclusion of exchange effects between the cluster and the projectile electrons. 相似文献
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Ł. Kłosowski M. Piwiski D. Dziczek K. Wiśniewska M. Zubek S. Chwirot 《The European physical journal. Special topics》2007,144(1):173-177
New apparatus for electron–atom collision investigations
incorporating
the magnetic angle changing method into the coincidence
technique has been set-up.
Combination of the two enables measurements of Electron Impact Coherence
Parameters in the full range of
scattering angles.
First energy loss and coincidence spectra are presented. 相似文献