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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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原子碰撞中的取向参数的研究为原子碰撞动力学、受激原子态结构提供了丰富的信息.本文介绍近年来电子与原子碰撞受激原子态取向的特征,其中包括电子与轻原子低能小角度散射下取向的趋向性规则;自旋依赖的取向特点;重原子散射下的取向特点,就重原子散射下取向的趋向性规则的破坏做了简要的分析和讨论. 相似文献
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原子碰撞中的取向参数的研究为原子碰撞动力学、受激原子态结构提供了丰富的信息。本介绍近年来电子与原子碰撞受激原子态取向的特征,其中包括电子与轻原子低能小角度散射下取向的趋向性规则;自旋依赖的取向特点;重原子散射下的取向特点,就重原子散射下取向的趋向性规则的破坏做了简要的分析和讨论。 相似文献
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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. 相似文献
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从实验和理论上研究了受激布里渊散射(SBS)光脉冲波形.在Nd∶YAG调Q激光器中实验研究了SBS光脉冲波形随抽运光参数、结构参数和介质参数的变化规律,并利用SBS理论模型进行了数值模拟,实验与数值模拟结果的变化趋势基本一致.结果表明,抽运光能量越小,透镜焦距越短,镜-池间距越长,介质声子寿命越长,SBS光脉冲波形就越不容易出现调制现象.分析和讨论了抽运光参数、结构参数和介质参数对SBS光脉冲波形的影响机理.
关键词:
受激布里渊散射
脉冲波形
抽运光参数
结构参数 相似文献
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《原子与分子物理学报》2015,(4)
本文详细介绍计算电子碰撞激发散射截面的扭曲波玻恩近似(DWBA)理论模型,并对低能DWBA模型进行修正.利用修正的DWBA模型计算了电子碰撞激发氢原子和氦离子1s-2s和1s-2p的散射微分截面.将关于氢原子由基态到n=2态的电子碰撞激发散射微分截面与绝对实验测量数据比较,发现二者符合得很好,这验证了我们对DWBA修正的正确性.本文工作为拟合强场诱导的氦原子非序列双电离关联电子动量谱提供了有效的理论方法. 相似文献
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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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在考虑分子内原子间的几何屏蔽效应随电子入射能量变化的基础上, 提出了一种能够在中、高能区准确计算“电子-分子”散射总截面的可加性规则修正方法. 利用这一修正后的可加性规则并使用“电子-C, H, O, N原子”散射总截面的实验数据, 在50—5000 eV内计算了电子被NO, N2O, NO2和C2H6分子散射的总截面, 且将计算结果与实验结果及其他理论结果进行了比较. 结果表明, 利用这一方法修正过的可加性规则进行计
关键词:
电子散射
可加性规则
总截面
几何屏蔽效应 相似文献
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Measurements of electron spin polarization resulting from inelastic electron scattering by mercury (excitation of the 61 P 1 state, 6.7 eV energy loss) are reported. Differential cross sections and angular dependences of the polarization have been measured for incident energies of 25, 30, 50 and 180 eV. 相似文献
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M. Piwiński D. Dziczek Ł. Kłosowski S. Chwirot 《The European physical journal. Special topics》2013,222(9):2273-2277
Polarization analysis version of the electron-photon coincidence technique was applied to completely determine quantum state of zinc atoms excited to the 41P1 state by electron impact. We report first experimental values of Stokes parameters and Electron Impact Coherence Parameters (EICPs) for incident electron energy 80 eV. 相似文献
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Cross sections for electron impact excitation of lithium from the ground state 1s^22s to the excited states 1s2s^2, 1s2p^2, 1s2snp (n = 2-5), 1s2sns (n = 3 5), 1s2pns (n = 3-5), and 1s2pnp (n = 3-5) are calculated by using a full relativistic distorted wave method. The latest experimental electron energy loss spectra for inner-shell electron excitations of lithium at a given incident electron energy of 2500 eV [Chin. Phys. Lett. 25 (2008)3649] have been reproduced by the present theoretical investigation excellently. At the same time, the structures of electron energy loss spectra of lithium at low incident electron energy are also predicted theoretically, it is found that the electron energy loss spectra in the energy region of 55-57eV show two-peak structures. 相似文献
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A detailed theoretical study is carried out for electron interactions with formyl radical (HCO) with incident energies ranging from 0.01 to 5000 eV. This wide range of energy has allowed us to investigate a variety of processes and report data on vertical electronic excitation energies, dissociative electron attachment (DEA) and total cross-section along with scattering rate coefficients. We observed Ramsaur–Townsend minimum at 0.59 and 0.74 eV using DZP and cc-pDVZ basis sets, respectively. HCO has large number of low-lying excited states and the present study finds an overall good agreement with earlier reported data. In order to compute total cross-section, we have employed ab initio R-matrix method (0.01 to ~ 20 eV) and the spherical complex optical potential method (~ 10 to 5000 eV) employing static-exchange plus polarisation potential. The R-matrix calculations are performed using a close coupling method with the aid of 21 target states, 1191 configuration state functions and 195 channels. The DEA cross-sections of fragmentation of H?, excitation cross- sections and scattering rate coefficients are reported for the first time. Total cross section presented here will provide a reference data set over an extensive impact energy range. 相似文献
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《Nuclear Physics A》1987,464(3):395-414
Measurements of differential elastic and inelastic cross sections for neutron scattering from 16O at incident energies 18 to 26 MeV are presented. In addition to cross sections for neutron scattering differential cross sections for proton scattering up to 66 MeV are described in terms of phenomenological optical model potentials. At 24.5 MeV incident energy inelastic scattering up to 11.5 MeV excitation was measured. The elastic and inelastic compound nucleus contributions were examined. Direct inelastic scattering from the normal parity states was calculated using the DWBA and coupled-channel formalisms. The inelastic scattering cross section from non-normal parity state 2− was calculated using the coupled-channel formalism via multi-step processes. Cross sections due to inelastic scattering from some of the states, which are thought to be members of an excited state rotational band were calculated using both vibrational and rotational approaches and were compared. 相似文献
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A. R. Milosavljević F. Blanco D. Šević G. García B. P. Marinković 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(1):107-114
Differential cross-sections (DCSs) for elastic
scattering of electrons from tetrahydrofurfuryl alcohol (THFA),
which can be considered as an analogue molecule to DNA sugar
deoxyribose, were determined using crossed beam measurements for
incident energies from 40 eV to 300 eV and scattering angles from
30° to 110°. The relative DCSs were measured both as a
function of incident electron energy and scattering angle,
allowing absolute calibration of the whole data set via
normalization to a single point. The absolute calibration has been
performed according to calculated absolute DCSs obtained by the
corrected independent atom method using an improved quasifree
absorption model. The calculated data-set includes DCSs and
integral elastic and inelastic cross-sections in the incident
energy range from 5 eV to 5000 eV. The theoretical results agree
very well with the experimental ones, regarding the shape of DCSs.
Moreover, the same theoretical procedure has been used to obtain
DCSs for elastic electron scattering from a simpler deoxyribose
analogue tetrahydrofuran (THF), which agree very well, both in
shape and on the absolute scale, with the recent experimentally
obtained absolute DCSs [A.R. Milosavljević et al., Eur. Phys.
J. D 35, 411 (2005)]. The present results are also
compared with the recent theoretical data for THF and THFA.
Finally, according to both experimental and theoretical data, the
DCSs for elastic electron scattering from THFA and THF molecules
appear to be very similar both in shape and absolute scale. 相似文献
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The stimulated desorption of ions from gas phase and condensed phase H2O on Ni(111) has been examined theoretically and experimentally for the near threshold excitation region, 15 to 40 eV. The excited state potential energy curves have been calculated using configuration interaction for H2O and a restricted Hartree-Fock (RHF) approach for a variety of small clusters including (H2O)5 and NiH2O. Both proton yield and kinetic energy distributions have been measured for chemisorbed, ice phase, and gas phase water and are discussed in terms of specific electronic excitations corresponding to possible desorption pathways. For condensed phase water, the major proton desorption threshold occurs at 20–21 eV and is due to surface predissociation. The final state potential energy curves reached in this process are, in general, described by two electron excitations from the ground state and are thus not dipole allowed. At threshold, these potential energy curves correspond to the excited states of the neutral rather than the ionized molecule. Above 28–29 eV, predissociation or shake-up involving excitations from the O 2s orbital contributes to the ion yield and can give rise to protons of high (7–8 eV) kinetic energy. 相似文献
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A fitting formula based on the Born approximation is used to fit the total cross sections for electron scattering by diatomic molecules (CO, N2, NO, O2 and HCl) in the intermediate- and high-energy range. By analyzing the fitted parameters and the total cross sections, we found that the internuclear distance of the constituent atoms plays an important role in the e-diatomic molecule collision process. Thus a new semi-empirical formula has been obtained. There is no free parameter in the formula, and the dependence of the total cross sections on the internuclear distance has been reflected clearly. The total cross sections for electron scattering by CO, N2, NO, O2 and HCl have been calculated over an incident energy range of 10–4000 eV. The results agree well with other available experimental and calculation data. 相似文献