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张涛 《原子与分子物理学报》2007,24(5):879-882
光与介质分子相互作用是一个活跃的研究领域,新的现象、技术和理论不断出现,原有理论对解释某些新的现象遇到困难.本文应用法拉第电磁感应原理研究了分子中电子云与光波之间的相互作用,提出了在光波作用下介质中存在的一种分子电流机制,这种电流的密度随磁场的时间变化率增加而增大,它不同于介质分子的极化电流和磁化电流.这些工作有助于深入认识光波与介质之间的相互作用. 相似文献
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本文在考虑了电子间交换相互作用以及内外壳层电子的不同屏蔽效应的基础上,根据变分原理确定了氩原子基态各电子的波函数,并利用电子云导体模型,计算了基态氩气的电子云等效体积和折射率,计算结果与实验值符合的很好. 相似文献
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本文在考虑了电子间交换相互作用以及内外壳层电子的不同屏蔽效应的基础上,根据变分原理确定了氩原子基态各电子的波函数,并利用电子云导体模型,计算了基态氩气的电子云等效体积和折射率,计算结果与实验值符合的很好。 相似文献
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基于扩展的一维SSH紧束缚模型结合非绝热的分子动力学方法,理论研究了共轭聚合物分子(PPV)在光脉冲作用下受激吸收和受激辐射的量子动力学过程.首先,设定分子初始处于基态,讨论了受激吸收过程中不同的电子受激跃迁模式与光激发脉冲的关系.通过对终态的分析,发现分子受激后只能产生电子-空穴的束缚态,包括:激子、双激子和高能激子.计算了各种激发态的产率,特别是,给出了各种激发态产率与光激发能量的定量关系.此外,基于实验,分别讨论了光激发强度对高能激子和双激子产率的影响,并与实验结果进行了比较.最后,设定分子初始分别处于激子和双激子态,研究了分子内定域能级之间的受激辐射过程,并简单讨论了激子和双激子受激辐射与光激发能量及强度的关系. 相似文献
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慢电子对甲烷分子的弹性散射截面计算 总被引:2,自引:1,他引:1
我们用甲烷分子的单中心波函数推导了投射电子与甲烷分子之间相互作用势的解析表达式,其中包含了投射电子与甲烷分子之间的静态库仑相互作用、极化作用及交换作用。我们计算了投射能量从0.005ev到10.00ev范围内的慢电子在甲烷分子场中运动的畸变波函数、分波相移(l≤5)、分波截面、总散射截面、动量转移截面及微分散射截面,得到了与实验数据符合得较好的结果。 相似文献
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有机化合物这类分子晶体能否具有超导电性,是多年来一直有所争论的问题.1980年世界上第一个有机超导体(TMTSF)2·PF。的发现终于揭开了这个谜,引起了科学家们极大的兴趣. 有机超导体的问世与七十年代发展起来的有机导体密切相关.在有机导体中,相同的平面型有机分子沿着某个方向相互平行堆砌成柱,柱中的π电子云强烈交叠,而相邻的柱间只有微弱的相互作用.这样的结构使它们与普通金属导体有着不同的导电性能,主要表现在(i)导电的强烈各向异性2(ii)低温出现Peierls-Frohlich型相变,金属态转化成绝缘体[1,2].因此,有机导体是一维金属电子理… 相似文献
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对中学物理电磁感应问题中比较复杂的模型,其能量转化也相对复杂.如系统中有的导体在克服安培力做功,有的安培力在对导体做功,而又可能涉及其他外力的功,如牵引动力、重力、摩擦力的功等.弄清这些系统的能量转化过程才能深入认识这些模型. 相似文献
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电子云不稳定性是强流质子加速器稳定运行的一个重大障碍。在电子云积累的过程中,二次电子多级倍增是电子云的主要来源。二次电子多级倍增机制可以用电子的运动和能量增益来分析。为了得到电子云的密度及分布,编写了一个模拟程序用来跟踪电子云的发展演化过程。分析了在质子束团作用下电子的运动,分析二次电子多级倍增的原因,并用模拟程序进行了计算,结果发现电子云与束团的纵向分布密切相关。 相似文献
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A theory based on the rate equation of free electron is used to analyze the process of free electron multiplication in optical materials under the laser irradiation, specially researching on the effect of avalanche ionization on the electron multiplication and material damage threshold. Numerical investigation with SiO2 is processed using this theoretical model, and damage thresholds under different avalanche models are analyzed. The result shows that during research on the energy charge between electron and electromagnetic field, the probability of avalanche ionization should be considered. Under this assumption, the numerical threshold gets well with the experimental result. 相似文献
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Jianqing Li Yuanlong Mo Yong Zhang 《International Journal of Infrared and Millimeter Waves》2002,23(9):1371-1383
By the method of the eigen mode expansion, a full three-dimensional (3-D) model has been developed that can be used to investigate the beam-wave interaction in a high-power, Ka-band relativistic coupled-cavity traveling-wave tube (TWT). In the tube studied by us, a sever in the interaction section is used to restrain the oscillation of RF electromagnetic fields between the input and output end. In this case, the asymmetric hybrid HTM11 mode has little impact on the main interaction process [1,2], so the RF electromagnetic fields mainly interacting with the modulated electron beam belong to the symmetric mode TM01. The presented model includes three-dimensional RF fields, three-dimensional electron motions, and improved three-dimensional space-charge fields including dc and ac space-charge fields. Moreover, this model can also calculate backward radiation excited by modulated electron beam and the direct effect of the transverse electron motion on the energy exchange. Our calculation results show that the space-charge field has evident effect on the interaction process, the transverse electron motion has some, and the backward radiation has little. 相似文献
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I. Tóth R. I. Campeanu V. Chiş L. Nagy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):351-354
Cross sections for the ionization of N2, CO and O2 diatomic molecules by electron impact are calculated. The applied distorted wave model is based on our previous studies for
positron impact, the molecular orbitals being described by Gaussian wavefunctions. Our study emphasizes the importance of
electron exchange and of using correct distorted waves for the ejected electron. 相似文献
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M. Yamazaki N. Kishimoto K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):47-57
Collisional ionization of styrene (phenylethylene), 2-vinylpyridine, and
4-vinylpyridine with metastable He*(23S) atoms were studied by means of
collision-energy/electron-energy resolved two-dimensional Penning
ionization electron spectroscopy. Collision energy dependence of partial
ionization cross-sections, which reflects the anisotropic interactions
between a He*(23S) atom and the target molecules, indicates that
attractive interaction for the out-of-plane access of a He*(23S) atom
to phenyl group is stronger than that for the out-of-plane access to vinyl
group. Moreover, it was found for vinylpyridines that the attractive
interaction around π electrons became weaker than that for styrene, and
that the attractive interaction for the in-plane access to the nitrogen atom
is stronger than that for out-of-plane π-directions. However, in
2-vinylpyridine, the hydrogen atom of vinyl group prevents a He*(23S)
atom from approaching to the nitrogen atom along in-plane directions, and
thus the attractive interactions around the nitrogen atom were shielded by
the vinyl group. The experimentally observed anisotropic interactions were
qualitatively supported with ab initio model interaction potential calculations
between a Li (He*(23S)) atom and the target molecule. Concerning with
electronic structures of investigated molecules, the assignment of Penning
ionization electron spectrum for 4-vinylpyridine was discussed on the basis
of different behavior of collision-energy dependence of partial ionization
cross-sections, and the satellite ionization band in Penning ionization
electron spectra was also reported for styrene. 相似文献
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V. P. Krainov 《Journal of Experimental and Theoretical Physics》2010,111(2):171-179
The ionization of atoms in a low-frequency linearly polarized electromagnetic field (the photon energy is much lower than
the ionization potential of an atom) is considered under new conditions, in which the Coulomb interaction of an electron with
the atomic core in the final state of the continuum cannot be considered in perturbation theory in the interaction of the
electron with the electromagnetic field. The field is assumed to be much weaker that the atomic field. In these conditions,
the classical motion of the electron in the final state of the continuum becomes chaotic (so-called dynamic chaos). Using
the well-known Chirikov method of averaging over chaotic variations of the phase of motion, the problem can be reduced to
non-linear diffusion on the energy scale. We calculate the classical electron energy in the final state, which is averaged
over fast chaotic oscillations and takes into account both the Coulomb field and the electromagnetic field. This energy is
used to calculate the probability of ionization from the ground state of the atom to a lower-lying state in the continuum
using the Landau-Dykhne approximation (to exponential accuracy). This ionization probability noticeably depends on the field
frequency. Upon a decrease in frequency, a transition to the well-known tunnel ionization limit with a probability independent
of the field frequency is considered. 相似文献
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M. Ya. Amusia 《JETP Letters》2009,90(3):161-165
Hartree-Fock atom in a strong electric static field is considered. It is demonstrated that exchange between outer and inner
electrons, taken into account by the so-called Fock term affects strongly the long-range behavior of the inner electron wave
function. As a result, it dramatically increases its probability to be ionized. A simple model is analyzed demonstrating that
the decay probability, compared to the case of a local (Har-tree) atomic potential, increases by many orders of magnitude.
As a result of such increase, the ratio of inner to outer electrons ionization probability became not too small. It is essential
that the effect of exchange upon probability of inner electron ionization by strong electric field is proportional to the
square of the number of outer electrons. It signals that in clusters the inner electron ionization by strong field, the very
fact of which is manifested by e.g. high energy quanta emission, has to be essentially increased as compared to this process
in gaseous atomic objects. 相似文献
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The influence of electron correlation on the electrostatic interaction between closed shell molecules is studied using the relaxed electron densities of the coupled cluster singles and doubles (CCSD) model. The corresponding CCSD one-electron density matrices are efficiently computed without full four-index transformation by employing the generalized exchange and Coulomb operator technique. Using several representative van der Waals and hydrogen bonded complexes it was found that in most cases the convergence of the M?ller-Plesset expansion of the electrostatic energy, restricted to single, double and quadruple excitations, is satisfactory and the fourth-order triple excitation term is more important than the sum of the fifth- and higher-order contributions from CCSD theory. The importance of the CCSD correlation correction to the electrostatic energy was gauged by comparison of the total interaction energy computed by symmetry-adapted perturbation theory (SAPT) and by the super-molecular CCSD(T) approach (coupled cluster singles and doubles model with a non-iterative inclusion of triple excitations). Except for the CO and N2 dimers, very good agreement between the two sets of results is observed. For the difficult case of the CO dimer the difference between the SAPT and CCSD(T) results can be explained by the truncation of the SAPT expansion for the dispersion energy at second order in the intramonomer correlation operator. 相似文献
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The population of various electronic states of particles that arise during the capture of a single electron in hydrogen and
helium atoms, as well as hydrogen molecules, by Ar3+ and Ne3+ ions with an energy of several kiloelectronvolts was studied by collision spectroscopy, viz., precision analysis of kinetic
energy variation for ions formed as a result of interaction between ions and atoms. It is shown that single-electron capture
in many cases is a multielectron process accompanied by the rearrangement of a multiply charged ion core. It is found that
the triply charged Ne3+ ions formed as a result of ionization of Ne atoms by electron impacts are formed mainly in metastable states. The population
of excited states of particles during their multiple ionization should be taken into account in determining the characteristics
of various particles by the appearance potential method. Collision spectroscopy can be used for analyzing the metastable ion
impurities in ionic beams. 相似文献