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1.
S. H. Li C. Wang J. S. Liu X. X. Wang R. X. Li G. Q. Ni Z. Z. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,34(1-3):215-218
Using time-of-flight spectrometry, the interaction of intense femtosecond
laser pulses with argon clusters has been studied by measuring the energy
and yield of emitted ions. With two different supersonic nozzles, the
dependence of average ion energy
on cluster size
in a large range of
has been measured. The experimental results indicate that
when the cluster size
, the average ion
energy
Coulomb explosion is the
dominant expansion mechanism. Beyond this size, the average ion energy gets
saturated gradually, the clusters exhibit a mixed Coulomb-hydrodynamic
expansion behavior. We also find that with the increasing gas backing
pressure, there is a maximum ion yield, the ion yield decreases as the gas
backing pressure is further increased. 相似文献
2.
For a homogeneous quantum network of N subsystems with n levels each we consider separable generalized Werner states. A generalized Werner state is defined as a mixture of the totally mixed state and an arbitrary pure state
:
with a mixture coefficient
. For this density operator
to be separable,
will have an upper bound
. Below this bound one should alternatively be able to reproduce
by a mixture of entirely separable input-states. For this purpose we introduce a set of modules, each contributing elementary coherence properties with respect to a generalized coherence vector. Based on these there exists a general step-by-step mixing process for any
. For
being a cat-state it is possible to define an optimal process, which produces states right up to the separability boundary (
).Received: 3 December 2002, Published online: 29 July 2003PACS:
03.65.Ud Entanglement and quantum nonlocality (e.g. EPR paradox, Bells inequalities, GHZ states, etc.) - 03.67.-a Quantum information - 03.65.-w Quantum mechanics 相似文献
3.
Hyperfine structure and isotope shifts in five optical
transitions: 424.5 nm (
–
), 537.2 nm (
–
), 554.5 nm
(
–
), 560.9 nm
(
–
) and 666.0 nm
(
–
)
of Pb II have been measured. As a light source the discharge tube was used.
The hyperfine structure measurements were
performed using metallic isotope 207Pb. For isotope shifts
measurements natural lead was used. The high resolution spectral apparatus consisted of a silver
coated Fabry-Perot etalon and a grating spectrograph combined
with a CCD camera used as a detector. In the analysis of the
spectra a computer simulation technique was used. The hyperfine
structure observations yielded the splitting constants A for
seven levels of Pb II. The isotope shift studies enabled to
separate the mass and the field shifts and to determine values of
changes of the mean square nuclear charge radii. 相似文献
4.
We compute the one-loop
-functions describing the renormalisation of the coupling constant
and the frequency parameter
for the real four-dimensional duality-covariant non-commutative
-model, which is renormalisable to all orders. The contribution from the one-loop four-point function is reduced by the one-loop wavefunction renormalisation, but the
-function remains non-negative. Both
and
vanish at the one-loop level for the duality-invariant model characterised by
. Moreover,
also vanishes in the limit
, which defines the standard non-commutative
-quantum field theory. Thus, the limit
exists at least at the one-loop level.Received: 19 March 2004, Published online: 5 May 2004 相似文献
5.
Knoop M. Champenois C. Hagel G. Houssin M. Lisowski C. Vedel M. Vedel F. 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2004,29(2):163-171
The lifetime of the
-level in singly-ionized calcium has been measured by the electron-shelving technique on different samples of rf trapped ions. The metastable state has been directly populated by exciting the dipole-forbidden
transition. In ion clouds, the natural lifetime of this metastable level has been measured to be (
) ms. For the single-ion case, we determined a lifetime of (
) ms. The
-error bars at the 2%-level have different origins for the two kinds of experiments: data fitting methods for lifetime measurements in an ion cloud and control of experimental parameters for a single ion. De-shelving effects are extensively discussed. The influence of differing approaches for the processing of the single-ion quantum jump data on the lifetime values is shown. Comparison with recent measurements shows excellent agreement when evaluated from a given method.Received: 14 November 2003, Published online: 24 February 2004PACS:
32.70.Cs Oscillator strengths, lifetimes, transition moments - 32.80.Pj Optical cooling of atoms, trapping 相似文献
6.
The position of high-energy critical minimum in elastic electron-argon scattering was investigated both experimentally and theoretically. Differential cross-sections (DCSs) were measured as a function of both incident electron energy (40-150 eV) and scattering angle (
), in small steps around the critical minimum. The position of the high-energy critical minimum in elastic electron-argon scattering was experimentally found to be at
eV and
. To cover the energy and angular ranges of the present experiment, relevant relativistic ab initio calculations were carried out, based on the Dirac-Hartree-Fock method with the exchange calculated exactly. Target polarization is described by an ab initio potential taken from relativistic polarized orbital calculations. The calculated position of the high-energy critical minimum is
eV,
. It was shown that even slight difference of fixed scattering angle close to the critical point could affect significantly the energy dependent DCS. Discussion of behavior of DCS in the vicinity of the critical minimum was performed including convolution analysis in both energy and angle.Received: 31 October 2003, Published online: 20 April 2004PACS:
31.15.Ar Ab initio calculations - 34.80.Bm Elastic scattering of electrons by atoms and molecules 相似文献
7.
Over 100 high lying level energies of the lowest electronic states
and
in Cs2 are determined in a
-like scheme two-colour photoassociation spectroscopy. The results are analyzed with a coupled channel model using an asymptotic approach, based on nodal lines. From this analysis we determine the long range dispersion coefficient C6 to 6846.2
15.6 a.u. We also obtain the first experimental determination of the amplitude of the asymptotic exchange term.Received: 4 November 2003, Published online: 20 January 2004PACS:
34.20.-b Interatomic and intermolecular potentials and forces, potential energy surfaces for collisions - 32.80.Pj Optical cooling of atoms; trapping - 03.65.Ge Solutions of wave equations: bound states 相似文献
8.
V. R. Brown B. F. Gibson J. A. Carlson R. Schiavilla 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):289-291
The parity-non-conserving longitudinal asymmetry in proton-proton (p
p) elastic scattering is calculated in the lab energy range 0-350 MeV using contemporary, realistic strong-interaction potentials combined with a weak-interaction potential comprised of
- and
-meson exchanges as exemplified by the DDH model. Values for the
- and
-meson coupling constants,
and
, are determined from comparison with the measured asymmetries at 13.6 MeV, 45 MeV, and 221 MeV.Received: 30 September 2002, Published online: 22 October 2003PACS:
21.30.-x Nuclear forces - 24.80. + y Nuclear tests of fundamental interactions and symmetries - 25.40.Cm Elastic proton scattering 相似文献
9.
The ground state X
of NaCs was studied by laser induced fluorescence Fourier-transform spectroscopy. An accurate potential energy curve was
derived from more than 5000 transitions. This potential reproduces the experimental observations within their uncertainties
of
cm-1 and covers about 99.97% of the potential well depth. Few vibrational levels of the shallow state a
below the atomic ground state asymptote were observed. The identification is mainly done by the observed and quantitatively
interpreted molecular hyperfine structure applying atomic parameters of the ground states of Na and Cs. An estimated potential
curve for a
is reported which can be used together with that of X
for coupled channel calculations of cold collisions between Na and Cs. An example is given.
Electronic supplementary material to this article is available at and is accessible for authorized users.
Received: 10 September 2004, Published online: 23 November 2004
PACS:
31.50.Bc Potential energy surfaces for ground electronic states - 33.20.Kf Visible spectra - 33.20.Vq Vibration-rotation analysis
- 33.50.Dq Fluorescence and phosphorescence spectra
Supplementary tables (Tabs. I-III) are only available in electronic form at http: //www.eurphysj.org 相似文献
10.
C.-M. Ghim E. Oh K.-I. Goh B. Kahng D. Kim 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,38(2):193-199
We investigate a problem of data packet transport between a pair of vertices on scale-free networks without loops or with a small number of loops. By introducing load of a vertex as accumulated sum of a fraction of data packets traveling along the shortest pathways between every pair of vertices, it is found that the load distribution follows a power law with an exponent
. It is found for the Barabási-Albert-type model that the exponent
changes abruptly from
for tree structure to
as the number of loops increases. The load exponent seems to be insensitive to different values of the degree exponent
as long as
.Received: 4 February 2004, Published online: 14 May 2004PACS:
89.75.Fb Structures and organization in complex systems - 05.65. + b Self-organized systems - 02.10.Ox Combinatorics; graph theory 相似文献
11.
Measurements of the time-dependent CP-asymmetry in the decay
and its charge conjugate by the BELLE and BABAR collaborations currently yield
and
, characterizing the direct and mixing-induced CP-asymmetries, respectively. We study the implication of these measurements on the CKM phenomenology taking into account the available information in the quark mixing sector. Our analysis leads to the results that the ratio |P
c
/T
c
| involving the QCD-penguin and tree amplitudes and the related strong phase difference
in the
decays are quite substantial. Using the isospin symmetry to constrain |P
c
/T
c
| and
, where
parameterizes the penguin-induced contribution, we present a fit of the current data including the measurements of
and
. Our best-fits yield
,
,
,
, and
. At 68% C.L., the ranges are
,
,
,
and
. Currently en vogue dynamical approaches to estimate the hadronic matrix elements in
decays do not provide a good fit of the current data.Received: 5 April 2004, Published online: 14 July 2004A.Ya. Parkhomenko: On leave of absence from Department of Theoretical Physics, Yaroslavl State University, Sovietskaya 14, 150000 Yaroslavl, Russia. 相似文献
12.
M. Z.M. Kamali K. Ratnavelu Y. Zhou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):267-279
The recent theoretical work by Bartlett et al. [J. Phys. B 38, L95 (2005)] and the latest measurements on the reduced Stokes parameters
,
and
for 54.4 eV electron impact excitation of the 2p state atomic hydrogen by Williams and Mikosza [J. Phys. B 39, 4113 (2006)] has motivated the present work. A coupled-channel-optical calculation with 9 and 12 atomic states supplemented
with the continuum optical potentials for the stronger coupling channels has been performed. The calculated n = 2 and n =
3 differential cross sections and the reduced Stokes parameters are comparable with the state-of-the art calculations. There is closer agreement between the present calculations and the experimental measurements for the reduced
Stokes parameters
and
in the n = 2p excitation at 54.4 eV. The present CCO calculations also display good accord with the limited experimental
data for the reduced Stokes parameters in the n=3p excitation. 相似文献
13.
G.?J.?Naga Raju G.?A.?V.?Ramana Murty B.?Seetharami Reddy T.?Seshi Reddy S.?Lakshminarayana S.?Bhuloka Reddy
The L X-ray intensity ratios in the elements Hf, Ta, Re, Ir, Pt, Au and Pb due to proton bombardment at energies from 1 to 5 MeV are measured and compared with the ECPSSR theoretical intensity ratios. The L
/L
l
intensity ratios obtained in the present work are in good agreement with theoretical values while the L
/L
and L
/L
intensity ratios are consistently lower than the theoretical values. This deviation may be explained in terms of multiple ionization effects in M, N and O shells.Received: 27 March 2004, Published online: 6 July 2004PACS:
32.80.Hd Auger effect and inner-shell excitation or ionization - 32.30.Rj X-ray spectra - 41.75.-i Charged-particle beams - 41.75.Ak Positive-ion beams 相似文献
14.
We present new experimental data on the highly excited levels in mercury using the two-step laser excitation and optogalvanic detection technique in conjunction with a RF discharge cell. The 6s7s 3S1 intermediate level has been accessed from the 6s6p 3P2 metastable level that is collisionally populated in the mercury discharge in the presence of a buffer gas at a pressure of about 1 Torr. Two beams fromtwo different dye lasers pumped with a common excimer laser were passed through the discharge cell containing mercury vapors. The first laser was tuned to 6s7s 3S1 level whereas the second laser was scanned covering the wavelength region between 544-458 nm. We have observed the 6snp 3P0 (
), 6snp
(
), 6snp
(
) and 6snp
) Rydberg series. The 6snp
Rydberg series to such high n-value has been reported for the first time. The first ionization potential of mercury is determined from the 6snp
Rydberg series as 84184.15
0.05 cm-1. Some collisionally induced parity forbidden transitions have also been located that are identified as 6sns
(
) series.Received: 5 November 2003, Published online: 20 January 2004PACS:
31.50.-x Potential energy surfaces - 32.30.Jc Visible and ultraviolet spectra - 32.80.Rm Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) 相似文献
15.
Van Hooydonk G. 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,32(3):299-317
The historical importance of the original
quantum mechanical bond theory proposed by Heitler and London in 1927 as well
as its pitfalls are reviewed. Modern ab initio treatments of H-
systems are inconsistent with the logic behind algebraic Hamiltonians
H± =H 0 ± H for charge-symmetrical and charge-asymmetrical 4 unit charge systems
like H2 and H
. Their eigenvalues E± =E 0±
are exactly those of 1927 Heitler-London (HL) theory. Since these
2 Hamiltonians are mutually exclusive, only the attractive one can apply for stable natural molecular H2. A wrong choice leads to problems with antiatom
. In line with earlier results on band and line spectra, we now prove
that HL chose the wrong Hamiltonian for H2. Their theory explains the stability
of attractive system H2 with a repulsive Hamiltonian H0 + H instead
of with the attractive one H0-H, representative for
charge-asymmetrical system H
. A new second order symmetry effect is detected in
this attractive Hamiltonian, which leads to a 3-dimensional structure for
the 4-particle system. Repulsive HL Hamiltonian H+ applies at long
range but at the critical distance, attractive charge-inverted Hamiltonian
H- takes over and leads to bond H2 but in reality, H
, for which we give an analytical proof. This analysis confirms and
generalizes an earlier critique of the wrong long range behavior of
HL-theory by Bingel, Preuss and Schmidtke and by Herring. Another wrong
asymptote choice in the past also applies for atomic antihydrogen
, which has hidden the Mexican hat potential for natural hydrogen. This
generic solution removes most problems, physicists and chemists experience
with atomic
and molecular H
, including the
problem with antimatter in the Universe. 相似文献
16.
A pair
of interacting Kerr oscillators treated as a master coupler sending chaotic or hyperchaotic signals to its slave copy
is considered. We synchronize a with A and b with B through two communication channels
and
. The effect of synchronization is non-simultaneous, the pairs
and
have different times of synchronization. It is possible to synchronize an individual pair, for example,
when its communication channel
is turned off, provided that the second channel for the pair
is turned on. The resulted synchronization is termed induced. The efficiencies of the presented synchronization precesses are studied.Received: 20 February 2003, Published online: 29 April 2003PACS:
05.45.Xt Synchronizations; coupled oscillators - 05.45.Pq Numerical simulations of chaotic systems - 42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics 相似文献
17.
The distorted wave Born approximation (DWBA) with the spin averaged static exchange potential has been used to calculate the triple differential cross-sections (TDCSs) for Ne (2s
2) ionization by electron impact in coplanar to perpendicular plane symmetric geometry at 110.5 eV incident electron energy. The present theoretical results at gun angles
(coplanar symmetric geometry) and
(perpendicular plane geometry) are in satisfactory agreement with the available experimental data. A deep interference minimum appears in the TDCS in the coplanar symmetric geometry and a strong peak at scattering angle
caused by the single collision mechanism has been observed in the perpendicular plane geometry. The TDCSs at the gun angles
, and
are predicted.Received: 16 July 2002, Published online: 22 July 2003PACS:
34.80.Gs Molecular excitation and ionization by electron impact - 34.80.Dp Atomic excitation and ionization by electron impact 相似文献
18.
Based on the corrected sum rules and generalized virial identities, we derive an expression for all modes of excitation spectrum of interacting Bose gases at finite atom numbers in axially anisotropic potentials, in terms of the N-body ground state average. Using the variational Gaussian calculation for the ground-state wave function, its explicit analytic formulas are obtained. These results show clearly the dependence of excitation spectrum on the interaction strength parameter
and trap geometry parameter
for the system with N = 1 through
. For
and 1 the dependences have simple and intuitive physical interpretations. We compare the low-lying excitation spectra with the existing numerical results and make quantitative predications for future experiments and numerical simulation for higher-lying excitation modes.Received: 18 February 2004, Published online: 20 April 2004PACS:
67.40.Db Quantum statistical theory; ground state, elementary excitations - 67.90. + z Other topics in quantum fluids and solids; liquid and solid helium 相似文献
19.
A resonance search has been made in the
invariant-mass spectrum with the ZEUS detector at HERA using an integrated luminosity of
. The decay channels
and
(and the corresponding antiparticle decays) were used to identify
mesons. No resonance structure was observed in the
mass spectrum from more than 60 000 reconstructed
mesons. The results are not compatible with a report of the H1 Collaboration of a charmed pentaquark,
.Received: 14 September 2004, Revised: 29 September 2004, Published online: 9 November 2004 相似文献
20.
A. Ehresmann W. Kielich L. Werner Ph. V. Demekhin D. V. Omel''yanenko V. L. Sukhorukov K.-H. Schartner H. Schmoranzer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):235-246
Dispersed fluorescence from fragments formed after the de-excitation of the
1s-1π* resonances of N*O and NO* has been
measured in the spectral range of 118–142 nm. This range is dominated by
lines of atomic nitrogen and oxygen fragments and by the
bands in the NO+ ion which result from the participator Auger decay of the 1s-1π* resonances.
Ab-initio calculations of the transition probabilities between vibrational
levels during the reaction NO
N*O
⇒ NO
were used to explain the observed intensity dependence for the
fluorescence bands on the exciting-photon energy across
the resonances and on both v′ and v′′
vibrational quantum numbers. The multiplet structure of the 1s-1π* resonance and lifetime vibrational interference explain the observed exciting-photon energy dependence of the
fluorescence
intensity. A strong spin-orbit coupling between singlet and triplet states
of NO+ is proposed to reduce additional cascade population of the
state via radiative transitions from the
and
states and to explain
remaining differences between measured and calculated integral fluorescence
intensities. 相似文献