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1.
The energy level shifts of one-electron atomic particles H, He+, Li++, etc. which interact with a metal surface have been investigated. In the approximation of image charges, an operator describing
perturbations of atomic levels has been obtained. By numerically solving the Schro dinger equation, we have calculated energy
levels of H(1s), H*(n=2), and C5+(n) as functions of the distance between an atom and surface. Asymptotic behavior of atomic levels at large distances from the
surface has been studied. The linear Stark effect for excited states, which was earlier mentioned by A. V. Chaplik, has been
found and investigated in detail.
Zh. éksp. Teor. Fiz. 116, 236–256 (July 1999) 相似文献
2.
The photoionization and stabilization of a Rydberg atom in a strong laser field are investigated theoretically. The role of
Raman-type transitions between neighboring Rydberg levels via the continuum (Λ transitions) and via lower-energy resonant
Rydberg levels (V transitions) is analyzed. The conditions under which this phenomenon can be observed experimentally are determined. The characteristics
of stabilization due to V-type transitions are described.
Zh. éksp. Teor. Fiz. 114, 821–836 (September 1998) 相似文献
3.
We find the evolution of average atomic variables in the resonance fluorescence of a two-level atom excited by a superposition
of coherent states shifted in phase by π. A new effect is predicted, the quantum instability of the average atomic dipole moment, with a strong correlation between
atom and field being the reason. We propose different ways of verifying the effect in experiments involving high-Q optical and microwave cavities.
Zh. éksp. Teor. Fiz. 111, 1174–1189 (April 1997) 相似文献
4.
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
5.
Demonstration of the approximation of eliminating atomic excited populations in an atomben cavity system 下载免费PDF全文
Using the master equation approach to a V-type three-level atom inside a high-finesse single-mode cavity in the strong coupling condition, we demonstrate the approximation of eliminating populations of atomic excited states, which is widely used in the field of the atom-cavity systems [Hechenblaikner G, Gangl M, Horak P and Ritsch H 1998 Phys. Rev. A 58 3030]; Liu L W, Tan T and Xu Y 2008 J. Mod. Opt. 56 968; Cho J, Angelakis D G and Bose S 2008 Phys. Rev. A 78 062338. This is reflected in the deviation of the population δ, of which the value is 10-3~10-2. We further find the deviation of the dipole force and demonstrate that the deviation of atomic population will not notably affect the dipole force of the atom in the strong coupling condition. A relevant experimental case is also presented. 相似文献
6.
S. Ghosh Deb S. Roy C. Sinha 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):591-600
The dynamics of the electron impact multiphoton ionization of a hydrogen
atom in the presence of an intense laser field (e, n γ e) has
been studied theoretically for laser polarization parallel (||l\vert \vert^{l}) and perpendicular
(⊥r) to the incident momentum, with a view
to comparing (qualitatively) the results with the recent kinematically
complete experiments of H?hr et al. [Phys. Rev. Lett. 94, 153201 (2005)] for the He target. Significant laser modifications are
noted in the present doubly (DDCS) and the fully differential multiphoton
cross sections (TDCS) for both the geometries (||l\vert \vert^{l} and
⊥r). For most of the explored kinematics (chosen in accordance with
the experiment), the present binary peak intensity of the laser-assisted
multiphoton TDCS is significantly enhanced with respect to the field free
ones, in qualitative agreement with the experiment. Importance of the
multiphoton effects is also studied. The multiphoton cross sections in the
zeroth order approximation of the ejected electron wavefunction (CV) obeys
the Kroll Watson sum rule while it does not hold good in the corresponding
first order approximation (MCV). 相似文献
7.
Spectral Analysis for Systems of Atoms and Molecules Coupled to the Quantized Radiation Field 总被引:2,自引:2,他引:0
Volker Bach Jürg Fröhlich Israel Michael Sigal 《Communications in Mathematical Physics》1999,201(2):249-290
We consider systems of static nuclei and electrons – atoms and molecules – coupled to the quantized radiation field. The interactions
between electrons and the soft modes of the quantized electromagnetic field are described by minimal coupling, p→p−e
A (x), where A(x) is the electromagnetic vector potential with an ultraviolet cutoff. If the interactions between the electrons and the quantized
radiation field are turned off, the atom or molecule is assumed to have at least one bound state. We prove that, for sufficiently
small values of the fine structure constant α, the interacting system has a ground state corresponding to the bottom of its
energy spectrum. For an atom, we prove that its excited states above the ground state turn into metastable states whose life-times
we estimate. Furthermore the energy spectrum is absolutely continuous, except, perhaps,
in a small interval above the ground state energy and around the threshold energies of the atom or molecule.
Received: 3 September 1998 / Accepted: 17 March 1999 相似文献
8.
It has been shown by Yu. M. Golubev, M. I. Kolobov, and I. V. Sokolov, Zh. éksp. Teor. Fiz. 111, 1579 (1997) [JETP 84, 864 (1997)], that when an optical cavity is excited by external radiation from a sub-Poisson laser the cavity mode may be
in either a sub-Poisson or a Poisson stationary state. This is not important for a resonant medium which is excited into the
upper laser level while interacting with this mode inside the cavity. The degree of regularity of the excitation will be identical
to that of the initial light flux incident on the cavity, and this ultimately ensures the same sub-Poisson lasing as for strictly
regular pumping of the resonant medium.
Zh. éksp. Teor. Fiz. 113, 1223–1234 (April 1998) 相似文献
9.
Yu. Sherkunov 《Optics and Spectroscopy》2007,103(3):388-397
The potential of long-range interaction between two dissimilar atoms, one of which is excited, drops as 1/R
2 with the distance for the Casimir-Polder limit of large distances in comparison with the wave-length of atom transitions
(E.A. Power and T. Thirunamachandran, Phys. Rev. A 51, 3660 (1995)). It is shown that such a dependence, obtained with the help of perturbation technique, results in a divergence
for the interaction potential between an excited atom and a medium of dilute gas. We develop a nonperturbative method based
upon quantum Green’s functions (Yu. Sherkunov, Phys. Rev. A 72, 052703 (2005)) to calculate the interaction potential for an excited atom and a ground-state atom embedded in a dielectric
medium, taking into account the absorption of photons in the dielectric medium. The exponential suppression of the interaction
between the atoms is demonstrated. The force acting on an excited atom near the interface of dilute gas medium is calculated.
The result is no more divergent. The force between gas media in Casimir-Polder regime is calculated as well.
The text was submitted by the author in English. 相似文献
10.
M.-P. Gorza S. Saltiel H. Failache M. Ducloy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):113-126
A theory of van der Waals (vdW) interaction between an atom (in ground or excited state) and a birefringent dielectric surface
with an arbitrary orientation of the principal optic axis (C-axis) is presented. Our theoretical approach is based on quantum-mechanical linear response theory, using generalized susceptibilities
for both atom and electromagnetic field. Resonant atom-surface coupling is predicted for excited-state atoms interacting with
a dispersive dielectric surface, when an atom de-excitation channel gets into resonance with a surface polariton mode. In
the non-retarded regime, this resonant coupling can lead to enhanced attractive or repulsive vdW surface forces, as well as
to a dissipative coupling increasing the excited-state relaxation. We show that the strongly non-scalar character of the interaction
with the birefringent surface produces a C-axis-dependent symmetry-breaking of the atomic wavefunction. Changes of the C-axis orientation may also lead to a frequency shift of the surface polariton mode, allowing for tuning on or off the resonant coupling, resulting in a special type of engineering of surface forces. This is analysed here in the case of
cesium 6D
3/2 level interacting with a sapphire interface, where it is shown that an adequate choice of the sapphire C-axis orientation allows one to transform vdW surface attraction into repulsion, and to interpret recent experimental observations
based on selective reflection methods [H. Failache etal., Phys. Rev. Lett. 83, 5467 (1999)].
Received 24 January 2001 相似文献
11.
We study the annihilation of a fast positron and a K-electron resulting in the emission of a photon and a second K-electron. It is assumed that all electrons and positrons move in the Coulomb field of the nucleus and that the Coulomb parameter
αZ is much less than unity (α=1/137 is the fine-structure constant and Z is the atomic number). The electron-electron interaction, which is responsible for the ejection of the electron by the atom,
is taken into account in the first order of perturbation theory. We calculate the differential and total cross sections of
the process and construct the ratio of the cross sections of double and single ionization as a function of the energy of the
incident positron. Finally, we establish the high-energy limit of this ratio, equal to 0.34/Z
2.
Zh. éksp. Teor. Fiz. 113, 786–804 (March 1998) 相似文献
12.
V. A. Kovarskii 《Journal of Experimental and Theoretical Physics》1997,85(1):48-51
High-order optical-harmonic generation in nonmetallic films interacting with pulses of laser light is examined. The wave functions
of the current carriers in a crystal in an external electromagnetic field are chosen in the form of Volkov-Keldysh solutions.
An explicit expression for the intensity of the sth harmonic, which depends on the crystal parameters, is derived. A plateau and a cutoff effect, similar to those in the case
of harmonic generation on an isolated atom, have been detected. Finally, numerical estimates are made for GaAs films excited
by pulses of radiation from a carbon dioxide laser.
Zh. éksp. Teor. Fiz. 112, 89–96 (July 1997) 相似文献
13.
A general scheme is presented for using different numbers of ‘time slices’ for different degrees of freedom in a path integral evaluation of the Boltzmann operator for a large molecular system. This will be particularly useful, for example, in evaluating the ‘quantum instanton’ rate constant [cf. W.H. Miller, Y. Zhao, M. Ceotto, S. Yang. J. Chem. Phys., 119, 1329 (2003)] for H atom transfer reactions, or any applications involving atoms with largely differing masses. 相似文献
14.
S. V. Prants 《Journal of Russian Laser Research》1996,17(5):539-549
We treat the general dynamic behavior of an externally driven two-level atom with underlyingSU(2) symmetry in the context of dynamical-systems theory. The temporal evolution of an atom driven by a circularly polarized bichromatic laser field is shown to be regular by calculating the power spectra and the stroboscopic phase portraits in terms of theSU(2) group parameters. In contrast to that, the atomic dynamics is shown to be irregular (ergodic) in the case of a linearly polarized bichromatic laser field. Exhibiting a rich variety of regular and irregular motion, an externally drivenSU(2) dynamical system cannot be truly chaotic in the sense of sensitivity to the initial conditions. 相似文献
15.
A. V. Bezverbnyi I. M. Beterov A. M. Tumaikin I. I. Ryabtsev 《Journal of Experimental and Theoretical Physics》1997,84(3):437-447
We examine the theory of potential scattering of Rydberg atoms in a microwave field. The model of a three-level atom is employed
to calculate the radiative force emerging in the resonant coherent interaction with the microwave field for the case of a
two-photon resonance and high intensities, using the method of quasienergies of the system consisting of the atom and the
field. We determine the probabilities of Landau-Zener transitions in the spatial regions where under two-photon resonance
conditions the quasienergies of the atoms approach one another by a small quantity. We also study the dynamics of the variation
of the spatial profile of a beam of Rydberg atoms caused by resonant scattering. Finally, we give the results of the first
experimental observation of the variation of the transverse beam profile when Rydberg atoms pass through a nonuniform microwave
field formed in a rectangular waveguide and in resonance with the two-photon 36P–37P transition.
Zh. éksp. Teor. Fiz. 111, 796–815 (March 1997) 相似文献
16.
Hydrogenated amorphous silicon (a-Si:H) films have been irradiated with H+, B+, P+, and Ar+ ion beams. The accumulation and the annealing of irradiation-induced defects has been investigated through a series of electronic transport and PDS measurements. We find that for all projectiles damage accumulation is dominated by atomic displacement collisions with the damage saturating for energy transfers in excess of about 10 eV/target atom. Annealing at elevated temperatures causes the conductivity of doped and irradiated a-Si:H films to increase according to stretched exponential decay curves. All annealing parameters derivable from such fits scale with the energy originally dissipated into atomic displacement collisions. For energy transfers up to 10 eV/target atom the activation energy for annealing increases up to a saturation value and, at the same time, an increasing fraction of the irradiation-induced defects becomes stable against annealing at moderate temperatures (T
a<250° C). We discuss these results with respect to damage accumulation data in crystalline silicon (c-Si) and with regard to the annealing of metastable defects in a-Si:H. 相似文献
17.
KEVIN K. LEHMANN 《Molecular physics》2013,111(23):1991-1993
This paper presents correction terms for the effective potential for the translation and rotation of an impurity atom or molecule solvated in a helium nanodroplet that were previously published (Lehmann, K. K., 1999, Molec. Phys., 97, 645). The correction arises from changes in the total He-He potential energy of the displaced liquid as a function of the solute position within the droplet. For the alkali atoms, this buoyancy type correction removes the large barrier to ejection of the atom from the droplets, which is predicted if this term is neglected. 相似文献
18.
Presently available laser sources can yield powers for which the ponderomotive energy of an electrons
can be equal to or even larger than the rest energy mc
2 of an electron. Therefore it has become of interest to consider fundamental radiation-induced or assisted processes in such powerful laser fields. In the present work we consider laser-induced Compton scattering and laser-assisted electron atom scattering in such fields, assuming that the laser beam has arbitrary elliptic polarization. We investigate in detail the angular and polarisation dependence of the differential cross-sections of the two laser-induced or laser-assisted nonlinear processes as a function of the order N of absorbed or emitted laser photons
. The present work is a generalization of our previous analysis of Compton scattering and electron-atom scattering in a linearly polarized laser field [Phys. Rev. A 65, 022712 and 033408 (2002)].Received: 3 November 2002, Published online: 29 April 2003PACS:
34.50.Rk Laser-modified scattering and reactions - 34.80.Qb Laser-modified scattering - 32.80.Wr Other multiphoton processes 相似文献
19.
V. V. Ivanov A. V. Kutsenko I. G. Lebo A. A. Matsveiko Yu. A. Mikhailov V. P. Osetrov A. I. Popov V. B. Rozanov G. V. Sklizkov A. N. Starodub V. V. Nikishin V. F. Tishkin 《Journal of Experimental and Theoretical Physics》1999,89(4):689-695
The paper presents results of experiments performed on the Pico facility in which foils were heated by laser radiation, and
anomalously fast burn-through of foils by a structured laser beam was detected. Comparison with two-dimensional calculations
has allowed us to suggest a tentative mechanism for the effect under investigation. The targets in the experiments were thin
aluminum foils of thickness 3 to 40 μm. The flux density of laser radiation on the target surface varied between 1013 and 1014 W/cm2. We detected a strong dependence of the transmitted energy on the foil thickness and the shortening of the transmitted laser
pulse. Penetration of laser radiation through foils with thicknesses considerably larger than 3 μm has been observed, although it was stated in earlier publications [V. V. Ivanov, A. K. Knyazev, A. V. Kutsenko, et al., Kratk. Soobshch. Fiz. FIAN No. 7–8, 37 (1997)]; A. é. Bugrov, I. N. Burdonskii, V. V. Gol’tsov et al., Zh. éksp. Teor. Fiz. 111, 903 (1997) [JETP 84, 903 (1997)] that, at the laser radiation parameters used in our experiment, the evaporated layer of the foil could not be
thicker than 2 μm. Two-dimensional calculations have allowed us to interpret this effect in terms of local “piercing” of the target at spots
on the target surface where the radiation intensity has its peaks. The possibility of reducing these peaks by using a symmetrizing
prepulse is discussed in the paper.
Zh. éksp. Teor. Fiz. 116, 1287–1299 (October 1999) 相似文献
20.
The problem of the amplification of high harmonics generated during the above-threshold ionization of atoms in a high-power
laser wave field is examined for the first time. An estimate of the gain coefficient as a function of the parameters of the
atom beam and the pump wave is given.
Zh. éksp. Teor. Fiz. 115, 1630–1641 (May 1999) 相似文献