共查询到20条相似文献,搜索用时 62 毫秒
1.
E. A. Andreev P. V. Kashtanov B. M. Smirnov 《Journal of Experimental and Theoretical Physics》2006,103(4):574-579
The lifetime of a molecule consisting of two Rydberg atoms with respect to electron release is determined from computer simulation
of two classical electrons in the field of Coulomb centers. From this, the cross section of the Penning process of collision
of two Rydberg atoms with electron release is obtained. The rate constant for ionization of Rydberg atoms is evaluated for
the Rydberg plasma within the Thomson model. On the basis of these processes, the kinetics is analyzed for the decay of a
Rydberg plasma. Comparison with experimental data shows that these decay processes are responsible for the first stage of
the decay of a magnetized and nonmagnetized Rydberg plasma located in a magnetic superconducting trap, whereas other processes
become important at a subsequent stage of the plasma evolution.
This article was submitted by the authors in English. 相似文献
2.
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
3.
We report the creation of an interacting cold Rydberg gas of strontium atoms. We show that the excitation spectrum of the inner valence electron is sensitive to the interactions in the Rydberg gas, even though they are mediated by the outer Rydberg electron. By studying the evolution of this spectrum we observe density-dependent population transfer to a state of higher angular momentum l. We determine the fraction of Rydberg atoms transferred, and identify the dominant transfer mechanism to be l-changing electron-Rydberg collisions associated with the formation of a cold plasma. 相似文献
4.
J.-H. Choi J. R. Guest G. Raithel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(1):19-26
Effective magnetic moments of drift Rydberg atoms in
strong magnetic fields are obtained for different energy and
angular-momentum states. Classical two-body trajectory
calculations and quantum-mechanical one-body calculations are
employed. For heavy atoms such as rubidium, the trapping dynamics
can largely be explained by the net magnetic moment due to the
cyclotron and the magnetron motion of the Rydberg electron. In
light Rydberg atoms such as hydrogen, the intrinsic two-body
nature of the dynamics becomes manifest in that the ionic motion
significantly contributes to the effective magnetic moment. Also,
light drift Rydberg atoms exhibit an anisotropic response to
field-inhomogeneities parallel and transverse to the
magnetic-field lines. The results are relevant to magnetic
trapping of Rydberg atoms in strong-magnetic-field atom traps. 相似文献
5.
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
6.
The inelastic transitions between hydrogenic energy levels of a Rydberg atom induced in collisions with ground-state atoms are considered. The corresponding transition probability and cross section are calculated using the Fermi pseudopotential to describe the atom-Rydberg-atom interaction and a quasiclassical expression for the density distribution of the Rydberg electron. 相似文献
7.
We have observed multiphoton ionization of the 5s core electron from a 5snd radial Rydberg wave packet of Sr atoms using a short optical pulse. When the outer nd electron is at its outer turning point the inner 5s electron is removed from the atom, and the outer electron is left in a Sr+ Rydberg state, but when the outer electron is at the inner turning point this does not occur. Analysis of the final Sr+ Rydberg states shows that the two electrons interact as the inner electron leaves, so that the outer electron is not simply projected onto the Sr+ Rydberg states. 相似文献
8.
J. E. Palmer 《Molecular physics》2019,117(21):3108-3119
Matter-wave interferometry has been performed with helium atoms in high Rydberg states. In the experiments the atoms were prepared in coherent superpositions of Rydberg states with different electric dipole moments. Upon the application of an inhomogeneous electric field, the different forces on these internal state components resulted in the generation of coherent superpositions of momentum states. Using a sequence of microwave and electric field gradient pulses the internal Rydberg states were entangled with the momentum states associated with the external motion of these matter waves. Under these conditions matter-wave interference was observed by monitoring the populations of the Rydberg states as the magnitudes and durations of the pulsed electric field gradients were adjusted. The results of the experiments have been compared to, and are in excellent quantitative agreement with, matter-wave interference patterns calculated for the corresponding pulse sequences. For the Rydberg states used, the spatial extent of the Rydberg electron wavefunction was ~320?nm. Matter-wave interferometry with such giant atoms is of interest in the exploration of the boundary between quantum and classical mechanics. The results presented also open new possibilities for measurements of the acceleration of Rydberg positronium or antihydrogen atoms in the Earth's gravitational field. 相似文献
9.
An atomic streak camera has been constructed that operates from the near to the far infrared. The photocathode used in conventional streak cameras for the conversion of photons to electrons has been replaced by gas-phase atoms in a Rydberg state. The low binding energy of the electron in a Rydberg atom combined with the large photoionization cross section of a Rydberg atom makes Rydberg atoms suitable for use in an infrared streak camera. Operation of the streak camera is demonstrated at 2.6 microm, well beyond the spectral range of any conventional streak camera. 相似文献
10.
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
11.
12.
Signals of ultracold plasma are observed by two-photon
ionization of laser-cooled caesium atoms in a magneto-optical trap.
Recombination of ions and electrons into Rydberg atoms during the
expansion of ultracold plasma is investigated by using
state-selective field ionization spectroscopy. The dependences of
recombination on initial electron temperature (1--70 K) and initial
ion density ($ \sim $10$^{10}$ cm$^{ - 3})$ are investigated. The
measured dependence on initial ion density is $N^{1.547\pm 0.004}$
at a delay time of 5 $\mu $s. The recombination rate rapidly
declines as initial electron temperature increases when delay time
is increased. The distributions of Rydberg atoms on different values
of principal quantum number $n$, i.e. $n=30$--60, at an initial
electron temperature of 3.3 K are also investigated. The main
experimental results are approximately explained by the three-body
recombination theory. 相似文献
13.
We report on the trapping of long-lived strongly magnetized Rydberg atoms. 85Rb atoms are laser cooled and collected in a superconducting magnetic trap with a strong bias field (2.9 T) and laser excited to Rydberg states. Collisions scatter a small fraction of the Rydberg atoms into long-lived high-angular momentum "guiding-center" Rydberg states, which are magnetically trapped. The Rydberg atomic cloud is examined using a time-delayed, position-sensitive probe. We observe magnetic trapping of these Rydberg atoms for times up to 200 ms. Oscillations of the Rydberg-atom cloud in the trap reveal an average magnetic moment of the trapped Rydberg atoms of approximately -8microB. These results provide guidance for other Rydberg-atom trapping schemes and illuminate a possible route for trapping antihydrogen. 相似文献
14.
为描述里德伯Cs原子与CCl4分子碰撞电离实验研究中所发现的若干特征,对里德伯原子与分子碰撞的理论模型-准自由电子模型提出两点修正:(1)考虑原子实在碰撞过程中的作用,并且计入量子亏损;(2)考虑碰撞后正负离子的分离几率。利用修正的模型进行了理论计算,得到了与实验测量较为吻合的结果,。同时与其它文献结果进行了比较。 相似文献
15.
A computational procedure for controlling the stochastic ionization of one-dimensional single electron Rydberg atoms in the correspondence principle regime is developed. Using our procedure it is possible to suppress excitation and ionization of the one-dimensional Rydberg atom even in strong microwave fields for which ionization would otherwise be instantaneous. 相似文献
16.
Cold Rydberg atoms exposed to strong magnetic fields possess unique properties which open the pathway for an intriguing many-body dynamics taking place in Rydberg gases, consisting of either matter or anti-matter systems. We review both the foundations and recent developments of the field in the cold and ultracold regime where trapping and cooling of Rydberg atoms have become possible. Exotic states of moving Rydberg atoms, such as giant dipole states, are discussed in detail, including their formation mechanisms in a strongly magnetized cold plasma. Inhomogeneous field configurations influence the electronic structure of Rydberg atoms, and we describe the utility of corresponding effects for achieving tightly trapped ultracold Rydberg atoms. We review recent work on large, extended cold Rydberg gases in magnetic fields and their formation in strongly magnetized ultracold plasmas through collisional recombination. Implications of these results for current antihydrogen production experiments are pointed out, and techniques for the trapping and cooling of such atoms are investigated. 相似文献
17.
D. B. Tretyakov I. I. Beterov V. M. Entin I. I. Ryabtsev P. L. Chapovsky 《Journal of Experimental and Theoretical Physics》2009,108(3):374-383
This paper reports on the results of experiments with cold rubidium Rydberg atoms in a magneto-optical trap. The specific feature of the experiments is the excitation of Rydberg atoms in a small volume within a cloud of cold atoms and the sorting of measured signals and spectra according to the number of detected Rydberg atoms. The effective lifetime of the 37P Rydberg state and its polarizability in a weak electric field are measured. The results obtained are in good agreement with theoretical calculations. It is demonstrated that the localization of the excitation volume in the vicinity of the zero-magnetic-field point makes it possible to improve the spectral resolution and to obtain narrow microwave resonances in Rydberg atoms without switching off the quadrupole magnetic field of the trap. The dependence of the amplitude of dipole-dipole interaction resonances in Rydberg atoms on the number of atoms is measured. This dependence exhibits a linear behavior and agrees with the theory for a weak dipole-dipole interaction. 相似文献
18.
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
19.
20.
We observe strong energy-dependent quantum defects in the scaled-energy Stark spectra for |M| = 1 Rydberg states of barium atoms at three scaled energies: ε = 2.000,ε = 2.500 and ε = 3.000.In an attempt to explain the observations,theoretical calculations of closed orbit theory based on a model potential including core effect are performed for non-hydrogenic atoms.While such a potential has been uniformly successful for alkali atoms with a single valence electron,it fails to match experimental results for barium atoms in the 6snp Rydberg states with two valence electrons.Our study points out that this discrepancy is due to the strong perturbation from the 5d8p state,which voids the simple approximation for constant quantum defects of principle quantum number n. 相似文献