共查询到20条相似文献,搜索用时 156 毫秒
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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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慢电子与He和Ne原子弹性碰撞的极化作用及散射截面计算 总被引:1,自引:1,他引:0
李萍 《原子与分子物理学报》1993,10(4):2967-2971
本文对慢电子与原子碰撞的一种常用的极化势模型进行了修正,使其在近区描述的入射电子使靶原子的极化作用更符合实际。用此修正后的极化势,在0.2-30eV能量范围内,本文还计算了电子被He和Ne原子弹性散射的总截面和微分散射截面。结果有很大改进,与实验符合得较好,说明本文的极化势修正是合理的。 相似文献
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根据密度矩阵理论,导出了受激原子态P态密度矩阵元和P态退激辐射的光子密度矩阵元的Stokes参数,它们之间存在一种非常简单直接的关系,说明在电子-光子符合散射实验中,通过测量光子的Stokes参数,就可以描述受激P态电荷云分布和散射过程的动力学。According to the density matrix theory, the density matrix of photon emitted from excited atom P state and of P state were introdued in this paper. There were a simple direct relation between the two density matrices, which shows that the electron cloud shape of excited atomic state and scattering dynamics can be described through the observable Stokes parameters of photon in electron-photon coincidence experiment. 相似文献
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V. S. Iyudin Yu. E. Kandrashkin V. K. Voronkova V. S. Tyurin E. N. Kirichenko 《Applied magnetic resonance》2011,40(1):75-89
Photoinduced spin-polarized transient electron paramagnetic resonance (EPR) spectra of copper 5,10,15,20-tetrakis(3-pyridyl)porphyrin
(3PyNCu) in the frozen solution have been observed in the X-band. The time evolution and the temperature dependence of the
spectra have been studied. The effect of molecular oxygen in the frozen solution on the polarization pattern has also been
examined. The magnetic resonance parameters of the ground state of 3PyNCu have been obtained by comparing the experimental
continuous-wave and echo-detected EPR spectra with the numerical computations. The magnetic resonance parameters of the excited
states and the photoinduced polarizations have been investigated by time-resolved EPR (TREPR) spectroscopy and numerical analysis.
The experimental spectra have been considered as a sum of the polarized spectra of the ground and excited states. Our analysis
confirmed that the TREPR spectra consisted of two main patterns: the enhanced signal from the ground state and the multiplet
contribution belonging to the excited quartet state. 相似文献
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Resonances of a hydrogen atom in strong parallel electric and magnetic fields using B-spline basis sets 下载免费PDF全文
The B-spline basis set plus complex scaling method is applied to the numerical calculation of the exact resonance parameters Er and Г/2 of a hydrogen atom in parallel electric and magnetic fields. The method can calculate the ground and higher excited resonances accurately and efficiently. The resonance parameters with accuracies of 10^-9 - 10^-12 for hydrogen atom in parallel fields with different field strengths and symmetries are presented and compared with previous ones. Extension to the calculation of Rydberg atom in crossed electric and magnetic fields and of atomic double excited states in external electric fields is discussed. 相似文献
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Resonances of a hydrogen atom in strong parallel electric and magnetic fields using B-spline basis sets 下载免费PDF全文
The B-spline basis set plus complex scaling method is applied to the
numerical calculation of the exact resonance parameters $E_r}$
and $\Ga/2$ of a hydrogen atom in parallel electric and magnetic
fields. The method can calculate the ground and higher excited
resonances accurately and efficiently. The resonance parameters with
accuracies of $10^{-9}-10^{-12}$ for hydrogen atom in parallel
fields with different field strengths and symmetries are presented
and compared with previous ones. Extension to the calculation of
Rydberg atom in crossed electric and magnetic fields and of atomic
double excited states in external electric fields is discussed. 相似文献
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JETP Letters - A nonlinear resonance excited by an alternating spin-polarized current in a ferromagnetic nanocylinder whose magnetization comprises a magnetic vortex is studied theoretically. The... 相似文献
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It is shown that the Kerr rotation of spin-polarized electrons is modulated by the distance of the electrons from the sample surface. Time-resolved Kerr rotation of optically excited spin-polarized electrons in the depletion layer of n-doped GaAs displays fast oscillations that originate from interference between the light reflected from the semiconductor surface and from the front of the electron distribution moving into the semiconductor. Using this effect, the dynamics of the photogenerated charge carriers in the depletion layer of the biased Schottky barrier is measured. 相似文献
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利用过渡金属掺杂的硅基团簇, 构建了一种自旋分子结; 并利用第一性原理方法, 对其电子自旋极化输运性质进行了研究. 计算表明, 通过过渡金属掺杂可以有效地产生自旋极化电流, 磁性金属Fe和非磁性金属Cr和Mn掺杂的体系呈现出较明显的自旋极化透射现象, 但分子结的自旋极化输运能力与团簇孤立状态下的磁矩无一致性.从Sc到Ni的掺杂, 体系的自旋极化透射能力先增大后迅速减小, 在Fe掺杂的Si12团簇中出现最大值.
关键词:
硅团簇
自旋极化输运
密度泛函理论
非平衡格林函数 相似文献
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Ultracold collisions between spin-polarized Na atoms and vibrationally excited Na2 molecules are investigated theoretically, using a reactive scattering formalism (including atom exchange). Calculations are carried out on both pairwise additive and nonadditive potential energy surfaces for the quartet electronic state. The Wigner threshold laws are followed for energies below 10(-5) K. Vibrational relaxation processes dominate elastic processes for temperatures below 10(-3)-10(-4) K. For temperatures below 10(-5) K, the rate coefficients for vibrational relaxation (v=1-->0) are 4.8x10(-11) and 5.2x10(-10) cm(3) s(-1) for the additive and nonadditive potentials, respectively. The large difference emphasizes the importance of using accurate potential energy surfaces for such calculations. 相似文献
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P. V. Kashtanov M. I. Myasnikov B. M. Smirnov 《Journal of Experimental and Theoretical Physics》2009,108(1):18-26
The standard classical method of computer simulation is used for evaluation of the inelastic cross section in electron collisions
with a highly excited (Rydberg) atom. In the course of collision, the incident and bound electrons move along classical trajectories
in the Coulomb field of the nucleus, and the scattering parameters are averaged over many initial conditions. The reduced
ionization cross section of a Rydberg atom by electron impact approximately corresponds to that of atoms in the ground states
with valence s-electrons and coincides with the results of the previous Monte Carlo calculations. The cross section of an atom transition
between Rydberg atom states as a result of electron impact is used for finding the stepwise ionization rate constant of atoms
in collisions with electrons or the rate constant of three-body electron-ion recombination in a dense ionized gas because
these processes are determined by kinetics of highly excited atom states. Surprisingly, the low-temperature limit of electron
temperatures is realized when the electron thermal energy is lower than the atom ionization potential by about three orders
of magnitude, as follows from the kinetics of excited atom states.
The article is published in the original. 相似文献
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The method of relativistic optical potential is applied to studying elastic scattering of electrons by europium and ytterbium atoms in a wide range of collision energies up to 2 keV. The angular dependences of the scattering differential cross sections and the energy dependences of the scattering integral (total, elastic, momentum transfer, and viscosity) cross sections are calculated in both spin-polarized and spin-unpolarized approximations. It is shown that the spin-polarized approximation should be used to calculate the scattering cross sections at energies below 10 eV for a europium atom. The low-energy scattering of an electron by a europium atom is characterized by P-, D-, and F-wave shape resonances. For an ytterbium atom, the calculated cross sections are in good agreement with available experimental data and with those obtained by calculation in terms of the relativistic convergent close-coupling method. 相似文献