共查询到20条相似文献,搜索用时 31 毫秒
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Dehua Wang Kaiyun Huang Shenglu Lin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(3):699-706
The ionization of Rydberg hydrogen atoms near a metal surface at different scaled energies above the classical saddle point
energy has been discussed by using the semiclassical method. The results show that the atoms ionize by emitting a train of
electron pulses. In order to reveal the chaotic and escape dynamical properties of this system in detail, the sensitive dependence
of the ionization rate upon the scaled energy is discussed. As the scaled energy is close to the saddle point energy, the
ionization process of the hydrogen atom is nearly the same as the case of hydrogen atom in an electric field. There is only
a single pulse of electrons, with an exponentially decaying tail. With the increase of the scaled energy, the ionization rates
are similar to the case of the hydrogen atom in parallel electric and magnetic field, a series of electron pulses appear in
the ionization process. This is caused by classical chaos, which occurs for the metal surface. Our studies also suggest that
the metal surface can play the role of both the electric and the magnetic fields. Our theoretical analysis will be useful
for guiding experimental studies of the ionization of atoms near the metal surface. 相似文献
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We have studied the ionization of Rydberg hydrogen atom near a metal surface with a semiclassical analysis of photoionization microscopy. Interference patterns of the electron radial distribution are calculated at different scaled energies above the classical saddle point and at various atom-surface distances. We find that different types of trajectories contribute predominantly to different manifolds in a certain interference pattern. As the scaled energy increases, the structure of the interference pattern evolves smoothly and more types of trajectories emerge. As the atom approaches the metal surface closer, there are more types of trajectories contributing to the interference pattern as well. When the Rydberg atom comes very close to the metal surface or the scaled energy approaches the zero field ionization energy, the potential induced by the metal surface will make atomic system chaotic. The results also show that atoms near a metal surface exhibit similar properties like the atoms in the parallel electric and magnetic fields. 相似文献
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We study the ionization of helium Rydberg atoms in an electric field above the classical ionization threshold within the semiclassical theory.By introducing a fractal approach to describe the chaotic dynamical behavior of the ionization,we identify the fractal self-similarity structure of the escape time versus the distribution of the initial launch angles of electrons,and find that the self-similarity region shifts toward larger initial launch angles with a decrease in the scaled energy.We connect the fractal structure of the escape time plot to the escape dynamics of ionized electrons.Of particular note is that the fractal dimensions are sensitively controlled by the scaled energy and magnetic field,and exhibit excellent agreement with the chaotic extent of the ionization systems for both helium and hydrogen Rydberg atoms.It is shown that,besides the electric and magnetic fields,core scattering is a primary factor in the fractal dynamics. 相似文献
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Qiang Chen 《哲学杂志》2015,95(33):3712-3726
Based on the semiclassical analysis of photoionization microscopy, we study the ionization of the Rydberg hydrogen atom near a dielectric surface. The radial electron probability density distributions on a given detector plane are calculated at different scaled energies and near different dielectric surfaces. We find due to the interference effect of different types of electron trajectories arriving at a given point on the detector plane, oscillatory structures appear in the electron probability density distributions. With the increase in the scaled energy, more types of electron ionization trajectories appear and the oscillatory structure in the electron probability density distributions becomes complex. Besides, the dielectric constant of the dielectric surface can also affect the electron probability density distributions. Since the photoionization microscopy interference pattern recorded on the detector plane reflects the distribution of the square modulus of the transverse component of the electronic wave function, with the recorded interference pattern, we can investigate the ionization dynamics of the Rydberg atom near surfaces clearly. This study provides some reference values for the future experiment research on the photoionization microscopy of the Rydberg atom near dielectric surfaces. 相似文献
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Semiclassical Calculations of Autoionization Rate for Lithium Atoms in Parallel Electric and Magnetic Fields 下载免费PDF全文
By using a semiclassical method, we present theoretical computations of the ionization rate of Rydberg lithium atoms in parallel electric and magnetic fields with different scaled energies above the classical saddle point. The yielded irregular pulse trains of the escape electrons are recorded as a function of emission time, which allows for relating themselves to the terms of the recurrence periods of the photoabsorption. This fact turns to illustrate the dynamic mechanism how the electron pulses are stochastically generated. Comparing our computations with previous investigation results, we can deduce that the complicated chaos under consideration here consists of two kinds of seff-similar fractal structures which correspond to the contributions of the applied magnetic feld and the core scattering events. Furthermore, the effect of the magnetic field plays a major role in the profile of the autoionization rate curves, while the contribution of the core scattering is critical for specifying the positions of the pulse peaks. 相似文献
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Matrasulov DU 《Chaos (Woodbury, N.Y.)》2002,12(3):650-653
Chaotic autoionization of the relativistic two-electron atom is investigated. A theoretical analysis of chaotic dynamics of the relativistic outer electron under the periodic perturbation due to the inner electron, assumed to be on a circular orbit, based on the Chirikov criterion, is given. The diffusion coefficient, the ionization rate, and time are calculated. (c) 2002 American Institute of Physics. 相似文献
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Landau quantization and time dependence in the ionization of cold, strongly magnetized Rydberg atoms
The electric-field-ionization and autoionization behavior of cold Rydberg atoms of 85Rb in magnetic fields up to 6 T is investigated. Multiple ionization potentials and field-ionization bands reflecting the Landau energy quantization of the quasifree Rydberg electron are observed. The time-resolved and state-selective field-ionization study provides evidence of mixing and spin flips of the Rydberg electron. Spin-orbit coupling combined with mixing gives rise to a Feshbach-type autoionization of metastable positive-energy atoms. 相似文献
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本文采用多通道量子数亏损理论对Mg原子的J=3,3pnd自电离Kydberg序列间的相互作用进行了分析,研究了通道相互作用对于自电离态的线形,自电离速率的影响。考察了在电离限附近原子的特性以及在其两侧电子的波函数的连续性,获得了与实验相一致的自电离光谱。
关键词: 相似文献
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利用脉冲放电产生氩原子亚稳态4s2[3/2]°2和4s′2[1/2]°0,在610~670nm波长范围内,利用共振增强多光子电离和飞行时间质谱技术得到氩原子(2+1)REMPI谱.光谱分析表明所有谱线来源于氩原子4s2[3/2]2和4s′2[1/2]°0两个亚稳态向16个奇对称性里德堡态双光子跃迁,并标识所有谱线.同时首次在实验上观察到一个长序列的3p54s′2[1/2]°0→3p5nd2[1/2]°1(n=8~31)双光子跃迁.在实验技术上,提供了一种研究惰性气体原予以及其它原子高里德堡态和自电离态的新方法. 相似文献
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Analysis of autoionizing Rydberg states in the vacuum ultraviolet absorption spectrum of HCl and DCl
The photographic absorption spectrum of HCl and DCl above the first ionization limit (750 – 950 Å) has been analyzed. Two Rydberg series converging to the second ionization limit (2Σ+) have been identified. No analyzable rotational structure was observed, indicating that the autoionization rate is faster than the rotational period. The symmetries of the Rydberg states cannot be determined conclusively, but several possibilities are discussed. 相似文献
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T. Amthor J. Denskat C. Giese N. N. Bezuglov A. Ekers L. S. Cederbaum M. Weidemüller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(3):329-335
We investigate a possible mechanism for the autoionization of ultracold Rydberg gases, based on the resonant coupling of Rydberg
pair states to the ionization continuum.
Unlike an atomic collision where the wave functions begin to overlap,
the mechanism considered here involves only the long-range dipole
interaction and is in principle possible in a static system.
It is related to the process of intermolecular Coulombic decay (ICD).
In addition, we include the interaction-induced motion of the atoms and the effect of multi-particle systems in this work.
We find that the probability for this ionization mechanism can be increased in many-particle systems featuring attractive
or repulsive van der Waals interactions. However, the rates for ionization through resonant dipole coupling are very low.
It is thus unlikely that this process contributes to the autoionization of Rydberg gases in the form presented here, but it
may still act as a trigger for secondary ionization
processes.
As our picture involves only binary interactions, it remains to be investigated if collective effects of an
ensemble of atoms can significantly influence the ionization probability.
Nevertheless our calculations may serve as a starting point for the investigation of more complex systems, such as the coupling
of many pair states proposed in [P.J. Tanner et al., Phys. Rev. Lett. 100, 043002 (2008)]. 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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基于五步激光共振激发,经由中间态(Xe) 5d6d~3F_2的一价镧离子光谱,分析了该实验谱,确定了一价镧离子一强一弱两个自电离里德伯系列.同时利用多通道量子亏损理论(MQDT)框架下的相对论多通道理论(RMCT)计算,标识了这两个自电离里德伯系列,强的自电离里德伯系列标识为5dnp(5/2,1/2)_3和/或5dnp(5/2,1/2)_2,弱系列标识为为5dnf(5/2,5/2)_3和/或5dnf(5/2,5/2)_2.根据实验谱峰数据,发现有效量子数很高时,里德伯和自电离里德伯能级量子数亏损随激发能量不平滑变化,并分析了可能的原因. 相似文献
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Semiclassical calculation of ionisation rate for Rydberg helium atoms in an electric field 下载免费PDF全文
The ionisation of Rydberg helium atoms in an electric field above the classical ionisation threshold has been examined using the semiclassical method, with particular emphasis on discussing the influence of the core scattering on the escape dynamics of electrons. The results show that the Rydberg helium atoms ionise by emitting a train of electron pulses. Unlike the case of the ionisation of Rydberg hydrogen atom in parallel electric and magnetic fields, where the pulses of the electron are caused by the external magnetic field, the pulse trains for Rydberg helium atoms are created through core scattering. Each peak in the ionisation rate corresponds to the contribution of one core-scattered combination trajectory. This fact further illustrates that the ionic core scattering leads to the chaotic property of the Rydberg helium atom in external fields. Our studies provide a simple explanation for the escape dynamics in the ionisation of nonhydrogenic atoms in external fields. 相似文献
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The autoionization mechanisms of dense nP3/2 (n = 20–97) Rydberg gases of 87Rb atoms in the spontaneous evolution were investigated for the first time. By observing the characteristic time of the electrons generated through autoionization process, the dependence of autoionization mechanisms (black-body radiation, electron–Rydberg collision, and Penning ionization) on the principal quantum number n of initial nP states was demonstrated. The dependence on the number n in nP Rydberg atoms is similar to those in nD Rydberg atoms. 相似文献
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Correspondence between classical dynamics and recurrence spectra of Rydberg hydrogen atom near a metal surface 下载免费PDF全文
The chaotic behaviours of the Rydberg hydrogen atom near a metal surface are presented. A numerical comparison of Poincare surfaces of section with recurrence spectra for a few selected scaled energies indicates the correspondence between classical motion and quantum properties of an excited electron. Both results demonstrate that the scaled energy dominates sensitively the dynamical properties of system. There exists a critical scaled energy εc, for ε 〈 εc, the system is near-integrable, and as the decrease of ε the spectrum is gradually rendered regular and finally turns into a pure Coulomb field situation. On the contrary, if ε 〉 εc, with the increase of ε, the system tends to be non-integrable, the ergodic motion in phase space presages that chaotic motion appears, and more and more electrons are adsorbed on the metal surface, thus the spectrum becomes gradually simple. 相似文献