共查询到20条相似文献,搜索用时 31 毫秒
1.
K. Sacha J. Zakrzewski D. Delande 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(3):231-234
We show how a static electric field can be used to control the localization of nonspreading wavepackets of a hydrogen atom
driven by a linearly polarized microwave field. This allows for creation of wavepackets localized on fully stable resonance
islands which, at the same time, can easily be excited by a direct optical transition from a low lying state. A semiclassical
analysis is used to predict the energies and properties of such states.
Received: 27 November 1997 / Accepted: 27 January 1998 相似文献
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.-S.F. Obada A.M. Abdel-Hafez M. Abdelaty 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(3):289-294
Phase properties of the field interacting with a two-level atom in a lossless cavity Jaynes-Cummings model, taking into account
the level shifts produced by Stark effect with an additional Kerr medium for one-mode are studied using the phase formalism
of Pegg and Barnett. It is shown in particular that phase properties of the field reflect the collapse and revival phenomena.
The results for the time evolution of the phase probability distribution and the phase fluctuations are obtained. The effect
of Stark shift on the phase properties in both the absence and presence of a Kerr medium is analyzed. Phase localization is
found for certain choice of the parameters.
Received: 27 March 1998 / Revised: 8 June 1998 / Accepted: 9 June 1998 相似文献
4.
5.
S. Ring B. Schmidt H. Baumgärtel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(2):155-158
We have studied the ionization of Rydberg-excited xenon atoms in THz-laser fields and by quantum dynamical calculations. The
experimental threshold laser field strength for 10% ionization probability follows an n*-1.68 (1.04 THz) dependence (n* effective principal quantum number) with additional weak resonance structures and shows that ionization does not occur by
a Landau-Zener mechanism. At scaled frequencies of to 5.6 the simulated threshold fields for ionization in oscillatory fields show a dependence on the principal quantum number
n of n-4.1 to n-1.35.
Received: 17 February 1998 / Revised: 20 April 1998 / Accepted: 21 April 1998 相似文献
6.
K. Drese M. Holthaus 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(1):119-134
We develop adiabatic perturbation theory for quantum systems responding to short laser pulses, with or without a frequency
chirp. Our approach rests on lifting the time-dependent Schr?dinger equation to an extended Hilbert space, then applying standard
perturbational techniques to Floquet states in this extended space, and finally projecting back to the physical Hilbert space.
The same strategy also allows us to construct superadiabatic bases for monitoring the quantum evolution in the course of a
pulse. These bases provide a diagnostic tool for improving the efficiency of pulse-induced population transfer. The formalism
is applied to the selective excitation of molecular vibrational states by chirped laser pulses, which exploit either successive
single-photon resonances or a multiphoton resonance, and by a STIRAP-like process.
Received: 23 June 1998 / Revised: 18 August 1998 / Accepted: 25 August 1998 相似文献
7.
M. Bouzidi A. Makhoute M.N. Hounkonnou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):159-165
We study the influence of the laser polarization on the electron impact excitation of atomic hydrogen. Our method takes into
account the “dressing” of the target states by including the laser-atom interaction to first order time-dependent perturbation
theory, while the interaction of the laser field with the incident electron is treated to all orders by using the non relativist
Volkov function. The interaction of the fast projectile with the target atom is treated in the first Born approximation. The
calculations are performed via two distinct computations. The first one is based on a direct calculation, the second based on a Sturmian approach. Important
differences appear between the angular distributions depending on the polarization chosen.
Received : 17 february 1998 / Revised : 20 july 1998 / Accepted : 2 september 1998 相似文献
8.
G. Li S. Wu P. Zhou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):267-277
The dressed-state populations and the resonance fluorescence spectrum of a V-type three-level atom driven by a strong coherent
field and a weak stochastic one simultaneously are investigated. There can be significant population inversion due to the
effect of the stochastic field. The atomic resonance fluorescence spectrum can be controlled by adjusting the frequency difference
between the coherent field and the stochastic one and the coherent Rabi frequency. Peak suppression and line narrowing occur
under appropriate conditions.
Received 23 June 2000 and Received in final form 18 January 2001 相似文献
9.
M.N.R. Ashfold S.R. Langford R.A. Morgan A.J. Orr-Ewing C.M. Western C.R. Scheper C.A. de Lange 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(2):189-197
Resonance enhanced multiphoton ionization (REMPI) spectroscopy, preferably linked with kinetic energy analysis of the resulting
photoelectrons (REMPI-photoelectron spectroscopy (PES)), continues to make enormous contributions to our understanding of
the spectroscopy and, in many cases, the decay dynamics of small molecules in excited (normally Rydberg) electronic states.
Here we present results of recent REMPI and REMPI-PES studies involving the ammonia molecule which provide further illustration
of some of the many opportunities offered by these techniques.
Received: 28 January 1998 / Revised: 3 April 1998 / Accepted: 15 April 1998 相似文献
10.
F. Dugain M. de Boissieu K. Shibata R. Currat T.J. Sato A.R. Kortan J.-B. Suck K. Hradil F. Frey A.P. Tsai 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(4):513-516
The dynamics of the decagonal AlNiCo phase has been investigated on a single-grain quasicrystalline sample using inelastic
neutron scattering. The decagonal structure can be viewed as a periodic stacking of quasiperiodic planes. The anisotropy between
the modes propagating in the periodic and quasiperiodic directions is found to be much weaker than theoretically predicted.
A strong resonance splitting is observed at an energy transfer of 15 meV for transverse modes polarized in the quasiperiodic
plane.
Received: 18 November 1998 / Accepted: 27 November 1998 相似文献
11.
E. Peik 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(2):179-183
An electrodynamic trap is proposed that stores cold neutral atoms or nonpolar molecules in their ground state as well as in
excited states by means of the quadratic Stark effect. The trap uses an oscillating hexapole field and a superposed static
homogeneous field. The dynamics of an atom in this trap can be described as a harmonic oscillation in a static pseudopotential.
Stability criteria and sample parameters for a number of atomic species are given.
Received: 7 August 1998 / Received in final form: 7 January 1999 相似文献
12.
过光与物质相互作用的主方程计算了强场激励的二能级原子与单模腔耦合的稳态荧光谱。在腔场的强耦合作用下,三峰Mollow谱的每个成分都分裂为多重的,这种现象由腔场使原子修饰态能级漂移而导致的,荧光谱的具体结构则依赖于驱动场的拉比频率和原子-腔的耦合系数。 相似文献
13.
A. Lindner H. Freese G. Quehl D. Reiß K. Schiller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):99-112
The time evolution of a damped two-level atom coupled to a damped field mode at resonance is calculated analytically as well
as numerically in the basis of dressed states. We study the dynamics of the density matrix and of observables, e.g. the number of field quanta. For the initial states we consider the field to be in a Fock or Glauber state and the atom in
the ground or excited state. We show the significant influence of the damping on the well-known phenomena of this model, e.g. collapse and revival.
Received 22 January 2001 and Received in final form 16 May 2001 相似文献
14.
A matter-wave interferometer based on the dc-Stark effect 总被引:1,自引:0,他引:1
We present a new separated beam atom interferometer in which the recombination of the atomic wave packet is due to the dc-Stark
interaction of an induced atomic dipole with a cylindrically symmetric electric field of a charged wire. The fringe period
shows a weak power-law dependence on the de Broglie wavelength and the polarizability of the particles. We present a semiclassical
theoretical model for this interferometer which resembles the measured performance of the interferometer without free parameters.
A discussion of possible applications of this interferometer for atoms and molecules is given.
Received: 20 November 1998 / Published online: 8 September 1999 相似文献
15.
V.I. Yukalov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):83-91
An ensemble of resonance atoms is considered, which are doped into a medium with well developed polariton effect, when in
the spectrum of polariton states there is a band gap. If an atom with a resonance frequency inside the polariton gap is placed
into the medium, the atomic spontaneous emission is suppressed. However, a system of resonance atoms inside the polariton
gap can radiate when their coherent interaction is sufficiently strong. Thus the suppression of spontaneous emission for a
single atom can be overcome by a collective of atoms radiating coherently. Conditions when such collective effects can appear
and their dynamics are analysed.
Received 7 June 2000 相似文献
16.
T. Ouchterlony I.V. Zozoulenko C.-K. Wang K.-F. Berggren C. Gould A.S. Sachrajda 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(2):361-370
We study the conductance of a square quantum dot, modeling the potential with a self-consistent Thomas-Fermi approximation.
The resulting potential is characterized by level statistics indicative of mixed chaotic and regular electron dynamics within
the dot in spite of the regular geometry of the gates defining the dot. We calculate numerically, for the case of a quantum
dot with soft confinement, the weak localization (WL) correction. We demonstrate that this confining potential may generate
either Lorentzian or linear lineshapes depending on the number of modes in the leads. Finally, we present experimental WL
data for a lithographically square dot and compare the results with numerical calculations. We analyze the experimental results
and numerical simulations in terms of semiclassical and random matrix theory (RMT) predictions and discuss their limitations
as far as real experimental structures are concerned. Our results indicate that direct application of the above predictions
to distinguish between chaotic and regular dynamics in a particular cavity can not always lead to reliable conclusions as
the shape and magnitude of the WL correction can be strongly sensitive to the geometry-specific, non-universal features of
the system.
Received 13 May 1998 相似文献
17.
J.M. Mestdagh M. Berdah N. Auby C. Dedonder-Lardeux C. Jouvet S. Martrenchard-Barra D. Solgadi J.P. Visticot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):291-302
The photodissociation of a chlorine molecule in the environment of a xenon cluster has been studied experimentally using the
real time pump and probe technique through the formation of an XeCl reaction product. The photodissociating system is probed
in such a way that the movement of a single chlorine atom in the xenon environment is detected. Various XenCl2 cluster sizes have been investigated leading to the distinction between uncapped, half-capped and doubly capped structures
for these clusters. These structures have a profound influence on the photodissociation dynamics. Retrapping of one chlorine
atomic fragment and stabilization of the XeCl reaction product is only observed for the half and doubly capped clusters. The
experimental work is complemented by classical molecular dynamics calculations to get a full picture of the photodissociation.
Received: 17 February 1998 / Received in final form and Accepted: 28 July 1998 相似文献
18.
19.
M. Glück A.R. Kolovsky H.J. Korsch N. Moiseyev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):239-246
The paper discusses the metastable states of a quantum particle in a periodic potential under a constant force (the model
of a crystal electron in a homogeneous electric field), which are known as the Wannier-Stark ladder of resonances. An efficient
procedure to find the positions and widths of resonances is suggested and illustrated by numerical calculations for a cosine
potential, which are in excellent agreement with complex scaling resonance energies.
Received: 27 April 1998 / Revised: 21 July 1998 / Accepted: 3 August 1998 相似文献
20.
F.J. Arranz F. Borondo R.M. Benito 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(2):181-187
Low resolution features in the spectra of classically chaotic atomic and molecular systems are known to be related to recurrences
induced by classical periodic motions. In this paper we study how such characteristics reveal in the LiNC/LiCN isomerizing
molecular system, and describe how the transition from regularity to classical chaos that takes place in this system shows
up at quantum level in the structure of the corresponding wavefunctions in the form of “scars”. To this end we use some projection
techniques, based on the propagation of wave packets, which have been developed in our laboratory. In this way some regions
at the border of the chaotic region can be detected, in which the systematics of “scar” formation can be studied at a very
elementary level, without complications due to the high level density which are customarily used in this type of studies in
order to achieve the semiclassical limit.
Received: 16 March 1998 / Revised: 23 April 1998 / Accepted: 4 May 1998 相似文献