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1.
J.-G. Wang T.-Q. Chang C.-Z. Dong T. Kato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):167-171
A simplified relativistic configuration interaction method is used to study the dielectronic satellite transition processes.
In this method, the infinite resonant doubly excited states can be calculated, and furthermore, the whole high-n dielectronic satellite transition processes can be treated conveniently by interpolation (rather than extrapolation) in the
frame of Quantum Defect Theory. As an example, we calculate the contributions from high-n dielectronic satellites to the resonance line in helium-like iron, and the results are in good agreement with the experimental measurements.
Received: 16 April 1998 / Revised: 8 September 1998 / Accepted: 14 September
1998 相似文献
2.
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
3.
V. N. Lokhman D. D. Ogurok E. A. Ryabov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):59-67
We report about effective ionization of iodine atoms and CF3I molecules under the action of intense XeCl laser radiation (308 nm). The only ion fragment resulting from the irradiation
of the CF3I molecules is the I+ ion. We have studied the influence of the intensity, spectral composition, and polarization of the laser radiation used on
the intensity
of the ion signal and the shape of its time-of-flight peak. Based on the
analysis of the results obtained, we have suggested the mechanism of this
effect. The conclusion drawn is that the ionization of the iodine atoms by
the ordinary XeCl laser with a nonselective cavity results from a three- (2 + 1)-photon REMPI process. This process is in
turn due to the presence of accidental two-photon resonances between various spectral components of the laser radiation and
the corresponding intermediate excited states of the iodine atom. The probability of ionization of the atoms from their ground
state I(2P3/2) by the radiation of the ordinary XeCl laser is more than two orders of magnitude higher than the probability of their ionization
from the metastable state I*(2P1/2). The ionization of the CF3I molecules by the XeCl laser radiation occurs as a result of a four-photon process involving the preliminary one-photon dissociation
of these molecules and the subsequent (2 + 1)-photon REMPI of the resultant neutral iodine atoms. 相似文献
4.
E. Träbert U. Staude P. Bosselmann K.H. Schartner P.H. Mokler X. Tordoir 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(2):117-123
N
=3, intercombination transitions in Al-like ions of Au have been studied by time-resolved EUV spectroscopy of foil-excited ion
beams. Wavelengths and lifetimes are compared to the available relativistic calculations. The theoretical data are found to
be useful for guidance, but of clearly insufficient precision, in particular for the transition probabilities.
Received: 23 February 1998 / Accepted: 5 March 1998 相似文献
5.
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
6.
7.
S. Cohen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):31-38
Approximate analytical formulae describing the energy variation of line intensities, autoionization widths and lineshape asymmetries,
are derived for a Phase-Shifted Multichannel Quantum Defect Theory model composed of two closed interacting channels coupled
to two effective continua. This is accomplished by putting the two compatibility equation solutions, for the common phase
shifts of the two open channels, in such a form so the resonant behavior is attributed to one of them, the other accounting
for an energy dependent background. Then, the well-known procedures for the simpler case where only one continuum is considered
are applied, using only the resonant solution. The method is quite general and applicable to any MQDT model with two or more
open channels. The resulting analytical formulae are tested on experimental spectra of Sr, Ba and Cu and it is shown that
they are valid as long as: i) The resonances are non-overlapping, ii) The direct closed channel coupling is much stronger
than the indirect one through the continua and (when excitation matrix elements are involved) iii) The open channels excitation
strength is smaller or at least comparable to the closed channels one.
Received: 26 May 1998 / Accepted: 1st July 1998 相似文献
8.
L. Feng Y.-k. Ho 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):25-30
In this paper, ion-atom and ion-ion collisions in the presence of intense laser fields are qualitatively studied by Classical
Trajectory Monte Carlo (CTMC) simulations. It is found that in contrast to the field-free collisions, the colliding ion and
the target nucleus could absorb energy from the applied laser fields when the electrons escape from the collision system.
This result is explained in terms of Coulomb explosion induced by the enhanced ionization at the so-called critical internuclear
distance. Also, the corresponding energy gain cross-sections are evaluated.
Received: 7 October 1998 / Received in final form: 28 January 1999 相似文献
9.
O. Keller C. Mang M. Nikola G. Schulz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):309-319
Emission spectra following electron impact on molecules of the homologous series of fluoromethanes CHxF4-x with x=0-4 have been investigated from the near infrared at 700 nm to the ultraviolet VUV-spectral region at 100 nm. Earlier experimental
data for the visible and ultraviolet spectral region were revised and evaluated again on the basis of reliable new data for
the dynamic viscosity of the molecules. The measurement of absolute and relative cross-sections were systematically extended
into the VUV region from 100 nm to 200 nm. The examination of atomic lines as well as molecular band systems in the VUV gives
further insight into the dissociation mechanism and shows that many excited levels even of atomic and molecular species cannot
be populated directly, but only by transitions from higher-lying energy levels. Simple steric effects can be distinguished
from more complex transition phenomena.
Received: 25 February 1998 / Revised: 29 May 1998 and 18 June 1998 / Accepted: 23
June 1998 相似文献
10.
X. Cai X. Chen Z. Liu Z. Shen D. Yu S. Wang X. Ma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(1):23-28
The ratios of the multiple ionization cross-section to those of the single ionization of neon are measured for 2.0-8.0 MeV
and
(
q
= 2-5) ions bombardment. By means of the coincidence beween the charge state-selected scattered projectiles and recoil ions the
contribution of the electron capture is separated from the total multiple ionization. A theoretical method is proposed to
exclude the Auger transitions from the considered multiple ionization processes in the present work. The (q
/
v) dependence of the obtained ratios of the “pure” direct multiple ionization to those of the single ionization is discussed.
The electronic structure dependence of the electron transition occurring in ion-neon collisions is studied and discussed for
the symmetrical collision systems - and -.
Received: 4 June 1998 / Received in final form: 24 August 1998 相似文献
11.
M.V. Moskalets 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(4):645-649
The effect of an electrostatic energy (in the geometrical capacitance approach) on a persistent current is considered. It
is shown that at high temperatures the current amplitude shows periodic dips as a function of the potential difference between
a ring and a reservoir. These dips correspond to a lift of the Coulomb blockade. In a minimum of a dips a current is periodic
in a magnetic flux with a period at any temperatures.
Received: 6 April 1998 / Revised: 5 June 1998 / Accepted: 21 July 1998 相似文献
12.
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
13.
F.A. Gianturco T. Mukherjee 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(2):211-218
The scattering of slow positrons from and NO molecules is treated using exact static interactions and a model potential for correlation-polarisation forces. The
quantum coupled equations for the elastic scattering are extended to vibrationally inelastic processes and the different excitation
probabilities are evaluated. Comparison with existing experiments for the NO target indicates that the present calculations
provide a realistic treatment of positron scattering below Ps formation and give computational estimates on the efficiency
of such projectiles in producing vibrationally excited molecules in the ambient gas.
Received: 23 April 1999 / Received in final form: 3 June 1999 相似文献
14.
A. Luis L.L. Sánchez-Soto 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(2):195-200
We reconsider the problem of the sum and difference of two angle variables in quantum mechanics. The spectra of the sum and
difference operators have widths of , but angles differing by are indistinguishable. This means that the angle sum and difference probability distributions must be cast into a range. We obtain probability distributions for the angle sum and difference and relate this problem to the representation
of nonbijective canonical transformations.
Received: 6 December 1997 / Revised: 15 April 1998 / Accepted: 7 May
1998 相似文献
15.
A. Tölle J. Wuttke H. Schober O.G. Randl F. Fujara 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(2):231-236
Structural relaxation in liquid orthoterphenyl is studied by means of coherent neutron time-of-flight and backscattering spectroscopy
over a large temperature range. Not only amplitude and relaxation time but also the spectral line shape show a significant
variation with wavenumber. These variations are correlated with the static structure factor, in qualitative accord with mode-coupling
results for simple liquids. Even far above the melting point, relaxation remains non-exponential.
Received: 5 January 1998 / Revised: 3 April 1998 / Accepted: 19 June 1998 相似文献
16.
S.M.S. da Costa M.H.F. Bettega 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(1):67-71
We report elastic integral, momentum transfer and differential cross sections for electron scattering by N2O for energies up to 50 eV. These results were obtained at the static-exchange approximation with the Schwinger Multichannel
Method with Pseudopotentials [M.H.F. Bettega, L.G. Ferreira and M.A.P. Lima, Phys. Rev. A 47, 1111 (1993)]. In general our results show good agreement with experimental data and with other theoretical results but some
discrepancies are found. We have also found a shape resonance around 4 eV in agreement with previous calculations using the R-matrix Method of Sarpal et al. [J. Phys. B 29, 857 (1996)]. On the other hand, the existence of a resonance at about 13 eV, clearly seen by the Schwinger Variational Iterative Method [Michelin et al., J. Phys. B 29, 2115 (1996)], can not be confirmed by our calculations. At this energy, our cross sections show a broad bump with no clear resonant behavior given by the eigenphase sum.
Received: 13 November 1997 / Revised: 13 March 1998 / Accepted: 9 April 1998 相似文献
17.
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
18.
M.J. Singh S.K. Goel R. Shanker D.O. Kataria N. Madhavan P. Sugathan J.J. Das D.K. Avasthi A.K. Sinha 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):7-13
Measurements were carried out to deduce the transverse kinetic energies of highly charged argon recoil ions produced in single
collisions of 120 MeV ions with argon atoms in which the post collision charge states of the projectiles were not determined. A time of flight
spectrometer was designed and fabricated to detect the charge states of recoils. Experimental procedures for optimizing the
spectrometer for extraction, transmission and detection of recoils are described. A simple approach for determining the transverse
kinetic energy of the recoil ions from FWHM of the peaks is reported. This method is shown to be independent of the choice
of collision partners and requires only the knowledge of the physical values of “optimized parameters” of time-of-flight spectrometer
used in the experiment. The transverse kinetic energy of the recoil ions determined from the present approach is found to
vary from 0.03 eV for to 4.02 eV for Ar10+. These values are compared with the results reported by earlier workers and are shown to follow a q2-behaviour up to a charge state q
=8+ of the recoil ions.
Received: 5 February 1998 / Revised: 8 June 1998 / Accepted: 11 June 1998 相似文献
19.
Chen Guo-xin P.P. Ong 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(2):153-156
Relativistic distorted-wave method was used to calculate the electron impact excitation collision strengths for transitions
2
s2
1
S0-2
s
2
p
3
P1 of Be-like isoelectronic ions. The target states were described, respectively, by 10-level, 46-level and 133-level MCDF configuration-expansion.
The relativistic continuum orbitals were calculated in the potential field of frozen target-ion charge distribution with semi-classical
exchange potential. The influence of the target states on this collision process along the isoelectronic sequence was investigated
in the above three MCDF configuration-expansion modes. It was found that the configurations in the n
=3 and the n
=4 complexes have great influence on both the high and the low Z ions but the influence is relatively small for intermediate Z ions. The latter phenomenon was attributed to competition between opposing correlation and relativistic effects on the collision
strengths.
Received: 25 February 1998 / Received in final form: 18 June 1998 相似文献
20.
A. Buchleitner K. Sacha D. Delande J. Zakrzewski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):145-157
We present a semiclassical analysis of the dynamics of Rydberg states of atomic hydrogen driven by a resonant microwave field
of linear polarization. The semiclassical quasienergies of the atom in the field are found to be in very good agreement with
the exact quantum solutions. The ionization rates of individual eigenstates of the atom dressed by the field reflect their
quasiclassical dynamics along classical periodic orbits in the near integrable regime, but exhibit a transition to nonspecific
rates when global chaos takes over in phase space. We concentrate both on the principal resonance where the unperturbed Kepler
frequency is equal to the driving field frequency and on the higher primary resonance The latter case allows for the construction of nondispersive wave packets which propagate along Kepler ellipses of intermediate
eccentricity.
Received: 23 June 1998 / Accepted: 10 November
1998 相似文献