共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
P.V. Grujić 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(4):441-450
We calculate rovibronic intrashell spectra of the triply highly excited atomic hydrogen dianion, helium anion and lithium
atom, within a simple semiclassical model. Zero-order electronic energy levels and half-lives are calculated for a number
of principal quantum numbers and approximate thresholds for the appearance of vibronic modes are estimated. Since no quantum-mechanical
and experimental data are available for the highly excited levels (N > 5), where the semiclassical models apply, no comparison with other results are possible at present. The problem of comparing
semiclassical and quantum-mechanical calculations for moderately large quantum numbers, which seem attainable by the present
day experimental technique, has been discussed.
Received: 16 September 1998 / Received in final form: 16 March 1999 相似文献
3.
A quantum hydrodynamical study is made of the dynamical changes of a helium atom interacting with lasers of two different
intensities, but having the same frequency. Under the intense laser field, electron density oozes out of the helium atom by
absorbing laser photons and getting promoted to higher excited states including the continuum. Under the superintense field,
electron density partly moves away from the helium nucleus but remains in the “quasi-bound” dressed states along with the
laser field, thus suppressing ionization. 相似文献
4.
High-Z helium like ions represent the simplest multi electron systems for studying the interplay between electron–electron correlations,
relativistic as well as quantum electrodynamical effects in strong fields. In contrast to the adjacent lithium like ions,
however, almost no experimental information is available about the excited states in the high-Z domain of the helium sequence. Here, we present a theoretical analysis of the X ray production and decay dynamics of the
excited states in helium like uranium. Emphasis has been paid particularly to the formation of the 3P0 and 3P2 levels by using electron capture into hydrogen like U91+. Both states are of interest for precise measurements on high-Z helium like ions in the future.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
6.
The features of the bremsstrahlung appearing during a collision of a fast charged particle with a hydrogen atom (or hydrogenic
ion) in an excited state are investigated. It is shown that the emission spectrum of photons with energies greater than the
ionization potential of a given excited state (except the 2s state) displays narrow lines, which are caused by de-excitation of the atom in an intermediate state. It is demonstrated
that the scattering of a charged particle on an excited hydrogen atom produces a feature which is not observed in the case
of scattering on a ground-state hydrogen atom. Expressions are obtained for the generalized dynamic polarizability of the
hydrogen atom and hydrogenic ions in the 1s, 2s, and 3s states. A method is developed for deriving expressions for the generalized dynamic polarizabilities of other excited states
through the use of the Coulomb Green’s function and representation of the electronic wave function in terms of the differentiation
of the generating functions of Laguerre polynomials. The bremsstrahlung cross sections for electrons and positrons colliding
with hydrogen atoms in the 1s, 2s, and 3s states are calculated.
Zh. Tekh. Fiz. 69, 7–13 (October 1999) 相似文献
7.
Filippo Giraldi Francesco Petruccione 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2014,68(2):1-9
Dynamic profiles of various chemical reactivity indices like chemical potential, chemical hardness, electrophilicity, susceptibility, etc., within a confined environment during the interaction of atoms with strong oscillating time dependent magnetic fields have been studied. In the present study hydrogen and helium atoms in ground state (n = 1), as well as in excited state (n = 20) are considered. Time-dependent Schrödinger equations are solved for the ground and excited states of hydrogen atom and the Rydberg state of the helium atom while a generalized nonlinear Schrödinger equation is solved for the ground state of the helium atom. Dirichlet type boundary condition has been used to implement confinement to the systems. With an increase in the degree of confinement the system gets harder and hence becomes more stable. Keeping the confinement radius fixed, systems get more stabilized in strong field compared to weak field. 相似文献
8.
A complete quantum solution provides all possible knowledge of a system, whereas semiclassical theory provides at best approximate solutions in a limited region. Nevertheless, semiclassical methods based on the work of Martin Gutzwiller can provide stunning physical insights in regimes where quantum solutions are opaque. Furthermore, they can provide a unique bridge between the quantum and classical worlds. We illustrate these ideas with an account of a theoretical and experimental attack on the paradigm problem of the hydrogen atom in strong magnetic and electric fields. 相似文献
9.
The Ryderberg electronic wave packet dynamics of hydrogen atom near helium surface in an electric field is investigated using the semiclassical method.The autocorrelation function is calculated when the photoionized electron is excited by a short laser pulse for different atom-surface separations.The results show that new recurrences appear because of the helium surface,and the number of recurrent peaks increases with the decrease in atom-surface distance.The new feature is ascribed to the bifurcation of new closed orbits in the classical dynamics of the photoionized electron.Therefore,surface properties have a significant effect on the spectrum of nearby atoms or ions. 相似文献
10.
Semiclassical calculation of ionisation rate for Rydberg helium atoms in an electric field
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
11.
K. B. Korotchenko 《Russian Physics Journal》1998,41(7):662-666
The primary goal of this work is to use a very well-known problem (the Kepler problem) to demonstrate the procedure for the
construction in theK-field formalism of the nonrelativistic approximation of the quantum mechanical model of the stationary states of the hydrogen
atom neglecting the spin properties of the electron. It is shown that the standard stationary states of the hydrogen atom
correspond to Lyapunov-stable trajectories of theK particle (point test particle, the classical model of the electron in the atom). In spite of the electron being considered
initially as a point particle without angular momentum, the internal logic of quantum mechanics in theK-field formalism requires the existence of the spin characteristics for the quantum mechanical model of the electron in the
Kepler problem, even in the nonrelativistic approximation.
Tomsk Polytechnic Institute. Translated fromIzvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 59–64, July, 1998. 相似文献
12.
Transition amplitudes and transition probabilities for the two-photon 1s–2s transition in the hydrogen atom and 11
s–21
s transition in helium atom have been calculated using a partial-closure approach. The dominant term is calculated exactly
and the remaining sum over intermediate states is calculated using a mean excitation energy. Our value of the transition amplitudes
agree within 2% with the exact results for the hydrogen case. Our value of the transition probability for hydrogen is 8.50
s−1 which is in good accord with its known value 8.226 s−1. For helium, the photon energy distribution of the metastable 21
s state is in good agreement with the accurate values. The corresponding transition probability is 53.7 s−1 which is in good agreement with the accurate value 51.3 s−1. 相似文献
13.
Coulomb deexcitation differential cross sections of excited muonic hydrogen in collisions with the hydrogen atom are studied
for the first time. In the fully quantum-mechanical close-coupling approach, both the differential cross sections for the
nl → n′l′ transitions and l-averaged differential cross sections have been calculated for the initial exotic atom states with n = 2–6 at kinetic energies of E
cm = 0.01–15 eV and for scattering angles of ϑcm = 0°–180°. The vacuum polarization shifts of the ns states are taken into account. The differential cross sections of the elastic and Stark scattering obtained in the same approach
are also presented. The main features of the calculated differential cross sections are discussed, and a strong anisotropy
of Coulomb deexcitation cross sections is predicted.
The text was submitted by the authors in English. 相似文献
14.
R. Y. Chiao S. J. Minter K. Wegter-McNelly L. A. Martinez 《Foundations of Physics》2012,42(1):173-191
Freely falling point-like objects converge toward the center of the Earth. Hence the gravitational field of the Earth is inhomogeneous,
and possesses a tidal component. The free fall of an extended quantum mechanical object such as a hydrogen atom prepared in
a high principal-quantum-number state, i.e. a circular Rydberg atom, is predicted to fall more slowly than a classical point-like
object, when both objects are dropped from the same height above the Earth’s surface. This indicates that, apart from transitions
between quantum states, the atom exhibits a kind of quantum mechanical incompressibility during free fall in inhomogeneous,
tidal gravitational fields like those of the Earth. 相似文献
15.
N. I. Shamrov 《Journal of Applied Spectroscopy》2006,73(1):68-78
An extension of the semiclassical model is proposed for superradiant Rayleigh scattering of light from a Bose-Einstein condensate
of dilute atomic gases. In contrast to the familiar models, this model takes into account the fact that the atom may be excited
by the scattered light and may acquire backward recoil momentum. The presented equations are solved analytically for the initial
(linear) stage of the process. The intensity of the scattered light and the efficiency of populating atomic states with different
momentum values are studied as a function of detuning from resonance.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 65–72, January–February, 2006. 相似文献
16.
M. B. Kadomtsev M. G. Levashova V. S. Lisitsa 《Journal of Experimental and Theoretical Physics》2008,106(4):635-649
We have developed a two-dimensional semiclassical model of the radiative-collisional cascade for hydrogen-like systems. We describe the collisions with electrons and ions by classical diffusion in the space of principal and orbital quantum numbers and use an iterative procedure that consistently takes into account the quantum nature of the radiative cascade for radiative transitions. The model establishes the correspondence between the quantum and classical approaches and indicates that the latter cannot be directly used to calculate the population kinetics of highly excited atomic states. Our calculations of the two-dimensional populations of highly excited atomic hydrogen states for selective, three-body, and photorecombination sources of population allow the data of one-dimensional kinetic models to be refined. The calculated intensities of recombination lines demonstrate the degree of nonequilibrium of the Rydberg state populations under typical astrophysical plasma conditions. 相似文献
17.
Tomographic approach to describing both the states in classical statistical mechanics and the states in quantum mechanics
using the fair probability distributions is reviewed. The entropy associated with the probability distribution (tomographic
entropy) for classical and quantum systems is studied. The experimental possibility to check the inequalities like the position–momentum
uncertainty relations and entropic uncertainty relations are considered. 相似文献
18.
This paper solves the problem of the interaction of an electron and positron via the field of soft and hard photons with emission
or absorption of a real photon. The interaction is interpreted as a third-order QED effect in the coordinate representation.
The role of intermediate states with positive and negative frequencies is studied. A general expression is derived for the
matrix elements of the operator of the effective electron-positron interaction energy for different types of quantum transitions.
The expression makes it possible to calculate the probabilities of the corresponding transitions in the nonrelativistic approximation.
Electric dipole transitions in the positronium atom accompanied by emission (absorption) of an optical photon are investigated.
Two-particle wave functions of the positronium atom are used to introduce the concept of polarization fields inside the positronium
atom. It is found that the polarization fields depend on the coordinates and time and on the choice of the pair of states
between which a quantum transition with emission or absorption of a photon takes place.
Zh. éksp. Teor. Fiz. 113, 471–488 (February 1998) 相似文献
19.
Akinori Fukushima Kosuke Hirai Masato Senami Akitomo Tachibana 《Surface science》2010,604(19-20):1718-1726
We study the behavior of a hydrogen atom adsorbed on aluminum nanowire based on density functional theory. In this study, we focus on the electronic structure, potential energy surface (PES), and quantum mechanical effects on hydrogen and deuterium atoms. The activation energy of the diffusion of a hydrogen atom to the axis direction is derived as 0.19 eV from PES calculations. The probability density, which is calculated by including quantum effects, is localized on an aluminum top site in both cases of hydrogen and deuterium atoms of the ground state. In addition, some excited states are distributed between aluminum atoms on the surface of the nanowire. The energy difference between the ground state and these excited states are below 0.1 eV, which is much smaller than the activation energy of PES calculations. Thus using these excited states, hydrogen and deuterium atoms may move to the axial direction easily. We also discuss the electronic structure of the nanowire surface using quantum energy density defined by one of the authors. 相似文献
20.
Recurrence spectra of He atoms in strong external fields 总被引:1,自引:0,他引:1
LIN Shenglu LI Hongyun WANG Dehua ZHAO Wenli & GAO Feng . Department of Physics Shandong Normal University Jinan China . Department of Mathematics Physics Shandong Institute of Architecture Engineering Jinan China 《中国科学G辑(英文版)》2004,47(4):477-484
1 Introduction The photo-absorption phenomenon of high Rydberg atoms in strong external fields has attracted much attention in recent years. The semiclassical closed-orbit theory[1,2] developed by Du and Delos has been extensively used to explain this phenomenon. This theory has successfully calculated and interpreted the photo-absorption spectra of H- in various external fields[3,4] and has been applied to describe the photo-excitation, wave packet dynamics of some atoms and molecules such… 相似文献