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1.
W. F. Mahmoudi N. Ben Nessib S. Sahal-Bréchot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):7-10
Owing to the increasing sensitivity of detectors,
accurate line profiles are needed for accurate stellar
atmospheres modelling and for laboratory and technological plasmas
as well. So, Stark broadening parameters of isolated lines of
complex atoms and ions within the impact and quasistatic
approximation are needed, even if the atomic abundance of the considered element is low.
Angular factors of the diagonal line strength entering the
quadrupole term appearing in the semi-classical expression of the
width of line broadened by electron or ion perturbers, are needed.
The aim of this paper is to extend the previous calculations of
this diagonal multiplet factor which were obtained for
configurations of the type ln and l1
nl2
m to
more complex configurations in LS coupling.
To study the Stark broadening of isolated lines in the impact and
quasistatic approximation, we use the semi-classical-perturbation
treatment, including both dipole and quadrupole contribution in
the expansion of the electrostatic interaction between the optical
electron and the perturber. We also use the Fano-Racah algebra.
Angular factors of the diagonal line strength entering the
quadrupole term appearing in the semi-classical expression of the
width of line broadened by electron or ion perturbers, are
calculated. New diagonal multiplet factor formulae for more
complicated configurations such as
(n1l1
n(LnSn)n2l2
m(LmSm)n3l3
p(LpSp))
are provided.
These formulae can enter the computer Stark semi-classical
perturbation codes. 相似文献
2.
S. Martin J. Bernard L. Chen A. Denis J. Désesquelles 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):1-6
Electron capture by Ar8+ in collisions with C60 fullerene has been investigated using coincident measurements of the number n of ejected electrons, the mass and charge of multicharged Cr+
60
recoil ions and their fragments Ci+
m and the final charge state of outgoing projectiles Ar(8-s)+ (). The number of captured electrons r is the sum of the numbers of stabilized and emitted electrons: r
=
n
+
s. The ratio n
/
s decreases by a factor three with s increasing from 1 to 7 showing that the multiply excited states populated by capture of a large number of electrons are rather
stable against auto-ionisation. Each kinetic energy spectrum of Ar+ and Ar2+ projectiles is composed of two peaks which we attribute to collisions “inside” and “outside” the C60 cage. The measured energy shift of the projectile keV is consistent with the corresponding energy loss keV in a carbon foil with an equivalent thickness. Inside collisions are characterized by a strong dissociation of recoil
ions into light monocharged fragments and by a high multiplicity of ejected electrons.
Received: 25 March 1998 / Received in final form and Accepted: 9 June 1998 相似文献
3.
Z. Németh Z. Homonnay F. Árva Z. Klencsár E. Kuzmann A. Vértes J. Hakl S. Mészáros K. Vad P. F. de Châtel G. Gritzner Y. Aoki H. Konno J. M. Greneche 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(3):257-263
Emission and transmission M?ssbauer studies of
La0.8Sr0.2CoO3-δ perovskites doped with ∼0.02
stoichiometric units of oxygen vacancy or 2.5% iron corroborate the
occurrence of electronic phase separation in these systems. The effect of
the small perturbation of the CoO3 sublattice with either iron ions or
oxygen vacancies on the bulk magnetization as well as on the M?ssbauer
spectra is in good agreement with the double exchange based cluster model.
The magnetoresistance does not show any peak near the Curie temperature, but
reaches -84% in a field of 7.5 T at T = 8 K. Below TC ≈
180 K the M?ssbauer spectra distinctly include the contribution from
paramagnetic and ferromagnetic regions, providing direct evidence for phase
separation. No contribution to the spectra from Fe4+ ions can be
observed, which is an unambiguous evidence that at low concentration iron
(either directly doped or formed from 57Co by nuclear decay) is
accommodated in the cobaltate lattice as Fe3+ ion. 相似文献
4.
A. Salmoun R. Brédy J. Bernard L. Chen S. Martin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):55-61
Electron capture processes in collision between slow
X7+ (X = N, O and Ne) ions and C60 fullerene have been
investigated using coincident measurements of the number n of ejected
electrons, the mass and charge of the multicharged C60
r+ recoil ions and their fragments Cm
i+ and the final charge state of the
outgoing projectiles X(q-s)+ (
). The
collision velocity is about 0.4 a.u. The partial cross-sections σr
s , corresponding to r electrons transferred to the projectile with only s electrons stabilized, have been measured. Cross-sections
for collisions “inside” and those “outside” the C60
cage have been separated by analyzing the kinetic energy of the outgoing
projectile. The mean final charge state for frontal collisions has been
measured to 3.1, 2.6 and 2.5 for N7+, O7+ and Ne7+
respectively. These results show the importance of the core effect on the
stabilisation processes of captured electrons. 相似文献
5.
M. M. Basko 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):641-654
New exact results are obtained for relativistic acceleration
of test positive ions in the laminar zone of a planar electron sheath
evolving from an initially mono-energetic electron distribution. The
electron dynamics is calculated against the background of motionless
foil ions. The limiting gamma-factor γp∞ of accelerated
ions is shown to be determined primarily by the values of the
ion-electron charge-over-mass ratio μ=meZp/mp and the initial
gamma-factor γ0 of the accelerated electrons. For μ>
1/8 a test ion always overtakes the electron front and attains
γp∞> γ0. For μ< 1/8 a test ion can
catch up with the electron front only when γ0 is above a
certain critical value γcr, which for μ≪1 can most
often be evaluated as
. In this model the protons and heavier
test ions, for which γcr> 10398 is enormous, always lag
behind the front edge of the electron sheath and have
γp∞< γ0; for their maximum energy an appropriate
intermediate asymptotic formula is derived. The domain of applicability
of the laminar-zone results is analyzed in detail. 相似文献
6.
P. Bogdanovich A. Kyniene R. Karazija R. Karpuskiene G. Gaigalas 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):175-183
The additional symmetry for the properties related to the ground state of the atom is considered taking into account many-electron
effects. Calculations of the I
4f, I
3d,I
2p,I
3p binding energies, 4f
N-15d - 4fN system differences and 2p, 3p electron affinities in the second order of perturbation theory and in the configuration interaction approximation have been
performed for the ground configurations with one open shell. The analysis of separate many-electron corrections for these
quantities and their variation along the sequences of atoms and ions shows that the main corrections maintain the considered
symmetry.
Received 18 January 1999 and Received in final form 17 July 1999 相似文献
7.
R. Parajuli S. Matt O. Echt A. Stamatovic P. Scheier T.D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):69-72
We have carried out measurements on metastable fragmentation of mass selected argon cluster ions which are produced by electron
impact ionization of a neutral argon cluster beam. From the shape of the fragment ion peaks (MIKE scan technique) one can
deduce information about the distribution of kinetic energy that is released in the decay reaction. In this study, for Ar
5
+ to Ar
15
+, it is Gaussian and thus we can calculate from the peak width the mean kinetic energy release 〈KER〉 of the corresponding
decay reactions. Using finite heat bath theory we calculate from these data the binding energies of the decaying cluster ions.
Received 20 November 2000 相似文献
8.
M. K. Srivastava 《Pramana》2004,63(5):1053-1062
An approximate simple scaling law is obtained for asymmetric (e, 3e) process on helium-like ions for double ionization by fast electrons. It is based on the equation (Z
′3π) exp[-Z(r1 + r2)],Z′ = Z – (5/16) for ground state wave function of helium-like ions and Z′2 scaling of energies. The scaling law is found to work very well if the lower energy electron is ejected along the momentum
transfer direction and the other one is ejected in the opposite direction. It also works quite well if this electron is ejected
within about 90° of the momentum transfer direction with the other electron going in the opposite direction. The scaling law
becomes increasingly accurate as the target nuclear charge and the energy increase. 相似文献
9.
H. -W. Hammer D. R. Phillips L. Platter 《The European Physical Journal A - Hadrons and Nuclei》2007,32(3):335-347
We use an effective field theory (EFT) which contains only short-range interactions to study the dependence of a variety of
three-nucleon observables on the pion mass. The pion-mass dependence of input quantities in our “pionless” EFT is obtained
from a recent chiral EFT calculation. To the order we work at, these quantities are the 1
S
0 scattering length and effective range, the deuteron binding energy, the 3
S
1 effective range, and the binding energy of one three-nucleon bound state. The chiral EFT input we use has the inverse 3
S
1 and 1
S
0 scattering lengths vanishing at m
π
crit = 197.8577 MeV. At this “critical” pion mass, the triton has infinitely many excited states with an accumulation point at
the three-nucleon threshold. We compute the binding energies of these states up to next-to-next-to-leading order in the pionless
EFT and study the convergence pattern of the EFT in the vicinity of the critical pion mass. Furthermore, we use the pionless
EFT to predict how doublet and quartet nd scattering lengths depend on m
π in the region between the physical pion mass and m
π = m
π
crit . 相似文献
10.
11.
A new mechanism of a “Coulomb explosion,” where ions are accelerated by the electric field separating charges at the magnetic
Debye radius r
B∼B/4πen
e, is proposed on the basis of a nonquasineutral model of electronic vortices in a magnetic field. It is shown by means of
numerical calculations that in the process of acceleration of the ions a collisionless shock wave, whose front has an effective
width of the order of δ∼r
B, determined by the breakdown of quasineutrality, is formed in a time of the order of ω
pi
−1
, where ωpi is the ion plasma frequency. The origin of such explosive dynamics is the formation of “holes” in the electron density at
characteristic times of the order of ω
pe
−1
(ωpe is the electronic plasma frequency) as a result of the generation of electronic vorticity by the Weibel instability of an
electromagnetic wave. Calculations for a laser pulse with intensity J∼6×1018 W/cm2 show that the ions expand in the radial direction with velocities up to 3.5×108 cm/s.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 10, 669–674 (25 November 1999) 相似文献
12.
S.A. Karamian J.S. Forster J.U. Andersen W. Assmann C. Broude J. Chevallier J.S. Geiger F. Grüner V.A. Khodyrev F. Malaguti A. Uguzzoni 《The European Physical Journal A - Hadrons and Nuclei》2003,17(1):49-56
Crystal blocking lifetime measurements have been made for highly excited Th nuclei with neutron number well removed from the
stability line. Thin W crystals were bombarded with 32S ions in the energy range 170-180 MeV and the yield of fission fragments was measured for emission close to a 〈111〉 axis.
The fission blocking dips are compared to the appropriately scaled ones for elastic scattering of the 32S beam ions and no significant difference is seen between the dips. This implies that the fraction of nuclei fissioning with
lifetimes longer than 10 as is less than 2%. Fission lifetimes are increased by viscosity in the nuclear mass flow and comparison
with a statistical model calculation indicates that the viscosity parameter, η, must be lower than for Th and U nuclei near
β-stability. The effect of the N = 126 magic number is discussed.
Received: 2 October 2002 / Accepted: 16 January 2003 / Published online: 29 April 2003 相似文献
13.
F. Fauth E. Suard V. Caignaert B. Domengès I. Mirebeau L. Keller 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(2):163-174
The oxygen deficient cobaltites LnBaCo2O5 (Ln = Tb, Dy, Ho) exhibit two successive crystallographic transitions at T
N
∼340 K and at T
CO
∼210 K. Whereas the first transition (P4/mmm to Pmmm) is related to the long-range antiferromagnetic ordering of the Co ions
(spin ordering), the second transition (Pmmm to Pmmb) corresponds to the long-range ordering of the Co2+ and Co3+ species (charge ordering) occurring in 1:1 ratio in the structure. The charge ordered (CO) state was directly evidenced by
the observation of additional superstructure peaks using neutron and electron diffraction techniques. The CO state was also
confirmed indirectly from refinement of high resolution neutron diffraction data as well as from resistivity and DSC measurements.
From the refined saturated magnetic moment values only, ∼3.7
and ∼2.7
, the electronic configuration of the Co ions in LnBaCo2O5 remains conjectural. Two pictures, with Co3+ ions either in intermediate spin state ( t
5
2g
e
1
g
) or in high spin state ( t
4
2g
e
2
g
), describe equally well our experimental data. In both cases, the observed magnetic structure can be explained using the
qualitative Goodenough-Kanamori rules for superexchange. Finally, in contrast to the parent Ln = Y compound [Vogt et al. , Phys. Rev. Lett. 84, 2969 (2000)], we do not report any spin transition in LnBaCo2O5 (Ln = Tb, Dy, Ho).
Received 13 December 2000 相似文献
14.
15.
Pavol Farkašovský 《Solid State Communications》2005,135(4):273-277
The extrapolation of small-cluster exact-diagonalization calculations is used to study the influence of doping on valence transitions in the spinless Falicov-Kimball model at nonzero temperatures. Two types of doping are examined, and namely, the substitution of rare-earth ions by nonmagnetic ions that introduce (i) one or (ii) none additional electron (per nonmagnetic ion) into the conduction band. It is found that the first type of substitution increases the average f-state occupancy of rare-earth ions, whereas the second type of substitution has the opposite effect. The results obtained are used to describe valence transition behavior of samarium in the hexaboride solid solutions Sm1−xMxB6 (M=Y3+, La3+, Sr2+, Yb2+) and a very good agreement of theoretical and experimental results is found. 相似文献
16.
A variational approach is developed for bound state calculations in three- and four-electron atomic systems. This approach
can be applied to determine, in principle, an arbitrary bound state in three- and four-electron ions and atoms. Our variational
wave functions are constructed from four- and five-body Gaussoids that respectively depend on six (r
12, r
13, r
14, r
23, r
24, r
34) and ten (r
12, r
13, r
14, r
15, r
23, r
24, r
25, r
34, r
35 and r
45) relative coordinates. The approach allows operating with the more than one electron spin functions. In particular, the trial
wave functions for the 1
S states in four-electron atomic systems include the two independent spin functions χ1 = αβαβ + βαβα − βααβ − αββα and χ2 = 2ααββ + 2ββαα − βααβ − αββα − βαβα − αβαβ. We also discuss the construction of variational wave functions for the excited
23
S states in four- electron atomic systems. 相似文献
17.
A. M. Badr A. A. EL-Amin A. F. Al-Hossainy 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):439-448
In this investigation, the synthesis process of the apyrazole derivative for
diphenylphosphino-methane hydrazine complexes
[ Ni(Cl)2{(Ph2P)2CHC(R1R2)NHNH2}] was
reported, and the obtained crystals were analyzed by X-ray diffraction. As a
result of the growth process, a set of complexes were formed. The structures
of these complexes are discussed on the basis of Elemental analysis (EA),
IR, 1H-NMR, 31P-NMR spectroscopic data and FAB mass spectra. The
compound under investigation shows typical semiconductor behavior as a
result of delocalization of the π-electrons in the structure. The
reflectance and transmittance spectra for the crystals were measured and
analyzed in the incident photon energy range 1.29 to 3.93 eV and in the
temperature range 77 to 300 K. The optical study revealed that the optical
transition is direct allowed. Below the absorption edge, the refractive
index as a function of wavelength was determined in the low energy region of
the used incident photon energy range. From the refractive index-wavelength
variations, the oscillator and dispersion energies of the refractive index
for the obtained crystals were determined. The static refractive index and
static dielectric constant were evaluated. 相似文献
18.
B. Canals D.A. Garanin 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(4):439-447
Thermodynamic quantities and correlation functions (CFs) of the classical antiferromagnet on the checkerboard lattice are
studied for the exactly solvable infinite-component spin-vector model, D↦∞. In contrast to conventional two-dimensional magnets with continuous symmetry showing extended short-range order at distances
smaller than the correlation length, r
ξ
c∝ exp(T
*/T), correlations in the checkerboard-lattice model decay already at the scale of the lattice spacing due to the strong degeneracy
of the ground state characterized by a macroscopic number of strongly fluctuating local degrees of freedom. At low temperatures,
spin CFs decay as <
>∝ 1/r
2 in the range a
0≪r≪ξ
c∝T
-1/2, where a0 is the lattice spacing. Analytical results for the principal thermodynamic quantities in our model are very similar with
MC simulations, exact and analytical results for the classical Heisenberg model (D = 3) on the pyrochlore lattice. This shows that the ground state of the infinite-component spin vector model on the checkerboard
lattice is a classical spin liquid.
Received 16 November 2001 and Received in final form 12 February 2002 相似文献
19.
D. Golberg P.S. Dorozhkin Y. Bando Z.-C. Dong C.C. Tang Y. Uemura N. Grobert M. Reyes-Reyes H. Terrones M. Terrones 《Applied Physics A: Materials Science & Processing》2003,76(4):499-507
Transport and field-emission properties of as-synthesized CNx and BNCx (x<0.1) multi-walled nanotubes were compared in detail. Individual ropes made of these nanotubes and macrofilms of those
were tested. Before measurements, the nanotubes were thoroughly characterized using high-resolution and energy-filtered electron
microscopy, electron diffraction and electron-energy-loss spectroscopy. Individual ropes composed of dozens of CNx nanotubes displayed well-defined metallic behavior and low resistivities of ∼10–100 kΩ or less at room temperature, whereas
those made of BNCx nanotubes exhibited semiconducting properties and high resistivities of ∼50–300 MΩ. Both types of ropes revealed good field-emission
properties with emitting currents per rope reaching ∼4 μA(CNx) and ∼2 μA (BNCx), albeit the latter ropes se- verely deteriorated during the field emission. Macrofilms made of randomly oriented CNx or BNCx nanotubes displayed low and similar turn-on fields of ∼2–3 V/μm. 3 mA/cm2 (BNCx) and 5.5 mA/cm2 (CNx) current densities were reached at 5.5 V/μm macroscopic fields. At a current density of 0.2–0.4 mA/cm2 both types of compound nanotubes exhibited equally good emission stability over tens of minutes; by contrast, on increasing
the current density to 0.2–0.4 A/cm2, only CNx films continued to emit steadily, while the field emission from BNCx nanotube films was prone to fast degradation within several tens of seconds, likely due to arcing and/or resistive heating.
Received: 29 October 2002 / Accepted: 1 November 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/51-6280, E-mail: golberg.dmitri@nims.go.jp 相似文献
20.
M. Kimura L. Pichl Y. Li H.-P. Liebermann R. J. Buenker I. F. Schneider 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):85-91
The positive water and hydronium ions are of interest in a
variety of chemical and biological applications. Here we study the
steric effect in charge transfer collisions, i.e. the spatial
dependence of single electron capture, in collisions mediated by
these ions. In particular, the steric effect is demonstrated in the
O+(2D)/H2 and H+/H2O charge transfer collisions in
the energy range of 100 eV/amu to 10 keV/amu. 相似文献