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1.
A. K.F. Haque M. A. Uddin M. A.R. Patoary A. K. Basak M. R. Talukder B. C. Saha K. R. Karim F. B. Malik 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):203-210
The recently modified Kolbenstvedt (MKLV) model [Eur. Phys. J. D 37, 361 (2006)], developed for electron impact ionization (EII) of the K-shell atomic targets, has been extended to generalize
its two parameters in terms of the electronic orbitals nl. The generalized MKLV
(GKLV) with two sets of the species independent parameters for the same nl,
one set for the ionization of inner orbits and another for the outermost orbit, is found
profoundly successful in accounting for the EII cross section data of the K, L and M-shell neutral atoms with atomic numbers
Z = 1-92 for the incident energies up to 1000 MeV
in a consistent manner. 相似文献
2.
R. Cheikh J. Hanssen B. Joulakian 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(3):203-208
The fivefold differential cross section (5DCS) of the ionisation by electron impact of atomic sodium is determined theoretically
for its fundamental 3s(2
S) state and the excited 3p(2
P) and 3d(2
D) states by a procedure which employs in the transition matrix element of the first order Born approximation, the correlated
double continuum (3C) wave function. This permits us to determine the statistical M-state population and the orientation and alignment tensors in (e,2e) detection. It is also shown that, the use of Gamow correlation term, in the independent particle (2C) model, reproduces,
only in some situations, the shape of the angular distribution of the 5DCS obtained by the (3C) wave function.
Received: 17 November 1997 / Received in final form: 16 March 1998 / Accepted: 21 March 1998 相似文献
3.
L.K. Jha B.N. Roy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):5-10
Electron impact single and double ionization cross-sections for magnesium have been calculated in the binary encounter model
using accurate expression for (cross-section for energy transfer ΔE) as given by Vriens. Hartree-Fock velocity distributions for the target electrons have been used throughout the calculations.
In case of double ionization contributions of inner shell ionization and Auger emission have been included in the present
work. The results obtained in case of single ionization are excellent and at the same time the double ionization cross-sections
show reasonably good agreement with the recent experimental observations. Substantiation of the viewpoint of Peach, and Boivin
and Srivastava that a vacancy in the 2p shell of magnesium leads to double ionization is a remarkable feature of the present investigation.
Received 9 October 2001 / Received in final form 8 January 2002 Published online 28 June 2002 相似文献
4.
M. R. Talukder S. Bose M. A.R. Patoary A. K.F. Haque M. A. Uddin A. K. Basak M. Kando 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):281-287
A simple empirical formula is proposed for the rapid
calculation of electron impact total ionization cross sections both for the
open- and closed-shell neutral atoms considered in the range 1≤
Z≤92 and the incident electron energies from threshold to about
104 eV. The results of the present analysis are compared with the
available experimental and theoretical data. The proposed model provides a
fast method for calculating fairly accurate electron impact total ionization
cross sections of atoms. This model may be a prudent choice, for the
practitioners in the field of applied sciences e.g. in plasma modeling, due
to its simple inherent structure. 相似文献
5.
J. P. Santos F. Parente 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(3):339-350
Total ionization cross sections of neutral phosphorus, arsenic,
antimony, and bismuth atoms by electron impact are reported and
compared to the only available experimental results by Freund et al. [Phys. Rev. A 41, 3575 (1990)]. These calculations take into account the possibilities that some
target atoms used in the experiments were in metastable states close
to the ground state, the excitation-autoionization of nsnp4
excited states may be substantial, and the ions produced in
experiments may be in excited, low-lying metastable states. The cross sections for direct ionization calculations are based
on
the BEB model by Kim and Rudd [Phys. Rev. A 50, 3954 (1994)].
Plane-wave Born cross sections scaled by the method developed by Kim
[Phys. Rev. A 64, 3954 032713 (2001)] are used to determine the
contributions from excitation-autoionization. The combination of the BEB model and the scaled Born cross sections
is in agreement with the experimental data by Freund et al. These theoretical data are useful to experimentalists and can
be
used to complete data tables needed for plasma or astrophysical
studies. 相似文献
6.
B. Nath S. Chattopadhyaya C. Sinha 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(1):31-36
Triple differential cross-sections (TDCS) of a hydrogenic (He+) ion has been studied by positron impact using coplaner geometry for both symmetric and asymmetric kinematics in the intermediate
and medium high incident energy region. TDCS has also been studied of He+ ion by electron impact for symmetric kinematics taking account of the electron exchange effect. The final state wavefunction
is chosen as the correlated 3-body Coulomb wavefunction satisfying the exact asymptotic boundary condition. The long range
Coulomb interaction in the initial channel between the ionic target and the projectile has also been taken into account properly.
For positron impact, the collision is found to be almost recoilless at lower incident energies, in contrast to the strong
recoil peak noted in the case of electron impact ionisation. For electron impact, the exchange effect is found to be significantly
high for equal energy sharing in the final channel.
Received 10 July 1999 and Received in final form 7 December 1999 相似文献
7.
J. B. Boffard M. F. Gehrke M. E. Lagus L. W. Anderson C. C. Lin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(2):193-198
This paper describes a method for reducing the influence of cascades on the measurement of electron excitation cross sections
using the optical method and a fast beam atomic target. By using a fast beam of target atoms one can reduce the influence
of cascades on a measurement, and estimate the cascade contribution to the excitation signal.
Received 19 April 1999 and Received in final form 10 August 1999 相似文献
8.
J. Martinez C. T. Whelan H. R.J. Walters 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):409-414
We consider (e,2e) processes on the 2s and 2p shells
of argon and magnesium. We present triple differential cross
sections in coplanar asymmetric geometry calculated in the Plane
Wave Born, 1st Born and Distorted Wave Born approximations. We show
that the currently available relative experiments can not easily
distinguish between these approximations. We make proposals for
relative experiments where the difference between these approaches
can be more readily observed. 相似文献
9.
K. M. Aggarwal F. P. Keenan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):205-213
In a recent paper, Verma et al. [Eur. Phys. J. D 42, 235 (2007)] have reported results for energy levels, radiative rates, collision strengths, and effective collision
strengths for transitions among the lowest 17 levels of the (1s22s22p6)3s23p6, 3s23p53d and 3s3p63d configurations of Ni xi. They adopted the civ3 and R-matrix codes for the generation of wavefunctions and the scattering process, respectively. In this paper, through two
independent calculations performed with the
fully relativistic darc (along with grasp) and fac codes, we demonstrate that their results are unreliable. New data are presented and their accuracy is
assessed. 相似文献
10.
J. Sun G. Yu Y. Jiang S. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):83-88
The additivity rule is employed to obtain the total (elastic+inelastic) cross-sections for positron scattering from molecules
including a number of diatomic, polyatomic molecules (H2, N2, HCl, CO2, NH3, SF6, CH4, C2H4 and C3H8) over an incident energy range of 10-1000 eV. The total cross-sections (TCS) of the constituent atoms of molecules are obtained
by employing a complex optical model potential (composed of static, polarization and absorption potential). The present results
are compared with experimental data and other theoretical calculations, good agreement is obtained in intermediate- and high-energy
region.
Received: 11 November 1997 / Revised: 23 March 1998 / Accepted: 16 June 1998 相似文献
11.
Summary Triple differential cross-section (TDCS) of hydrogen atom in its metastable (2S) state is studied theoretically by electron and positron impact for coplanar and asymmetric geometry. The final-state wave
function in the present model satisfies the asymptotic boundary condition for asymmetric geometry (i.e. fork
1≫k
2). In the absence of experiment, present results are compared with other existing theoretical results. Apart from the double-peaked
structure of the TDCS as in ground-state ionization, some interesting secondary structures are found, in conformity with other
theories for ionization from 2S state. 相似文献
12.
F. Giammanco F. Maccarrone R. S. Dygdala D. Dziczek S. Chwirot 《Il Nuovo Cimento D》1996,18(6):677-687
Summary We evaluate the role of electron-ion mutual interactions as a possible source of systematic errors in an experiment of electron
impact ionization and excitation of an effusive Ca beam. By monitoring photons resulting from the impact excitation of a Ca
resonant transition, the transmitted electron beam current by a sectored Faraday cup and total ion yields, we extract information
about elementary processes responsible for ionization. We show that our diagnosis allows us to monitor the influence of the
produced ionization on the elementary processes and on the density profile of the electro beam. 相似文献
13.
M. R. Talukder 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):167-172
The electron impact single ionization cross sections, on the helium isoelectronic He, Li1+, B3+, C4+, N5+, O6+, Ne8+, Na9+, Ar+16, Fe24+, Mo41+, Ag45+, and U90+ targets, are calculated modifying the simplified Bell (SBELL) model [Eur. Phys. J. D 46, 281 (2008)]. The results of the present analysis are compared with the available experimental and theoretical data. The
modified SBELL (MSBELL) model, incorporating the ionic correction factor in it, produces excellent agreement with the experimental
data and theoretical calculations for all the two-electron systems, neutral or ions. This model may be a prudent choice in
plasma modeling due to its simple inherent structure. 相似文献
14.
Calculation of dielectronic recombination cross sections and rate coefficients for heliumlike carbon
J.-G. Wang T.-Q. Chang Y.-Z. Qu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(3):231-235
A simplified relativistic configuration interaction method is used to calculate the dielectronic recombination cross sections
and rate coefficients for heliumlike carbon. In this method, the infinite resonant doubly excited states can be treated conveniently
in the frame of Quantum Defect Theory. Our calculated cross sections are in agreements with the experimental measurements
except for the 1s2lnl'(n=6,7) resonances. The total energy-integrated cross sections and rate coefficients over all dielectronic resonances are in
agreements with the experimental measurements within percent.
Received: 7 July 1997 / Revised: 7 October 1997 / Accepted: 8 December 1997 相似文献
15.
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
16.
H. Deutsch K. Becker T.D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(2):283-287
We report calculations of the electron-impact ionization cross-sections of selected dimers (homonuclear diatomic molecules)
and trimers (homonuclear triatomic molecules) using a method which relies only on macroscopic quantities in conjunction with
a “defect concept”. The empirically determined defect describes the deviation of the cluster (dimer, trimer) cross-sections
from a simple linear dependence on the cluster size. We compare the calculated cross-sections to experimental data for the
dimers S2 and F2 and the trimer O3 and we present predictions for the ionization cross-sections of Br2, I2, C2 and C3 for which no experimental data are available. Lastly, we extend the method to the calculation of ionization cross-sections
for the fullerenes C60 and C70.
Received 6 December 1999 and Received in final form 10 April 2000 相似文献
17.
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
18.
N. Verma A. K.S. Jha M. Mohan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):235-241
Electron excitation collision strengths for the transitions from the ground
state to the fine-structure levels of the 3s23p53d and
3s23p63d configurations in Ni XI are calculated using the
Breit-Pauli R-matrix method. Configuration interaction wavefunctions have
been used to represent the target states. The relativistic effects are
incorporated in the Breit-Pauli approximation by including one-body mass
correction, Darwin, and spin-orbit interaction terms in the scattering
equations. Collision strengths are tabulated at selected energies in the
range 10 to 75 Rydberg. Effective collision strengths are determined by
integrating collision strengths by assuming a Maxwellian distribution of
electron energies. The effective collision strengths are listed over a wide
temperature range (2×104-1×107 K) applicable to
astrophysical plasmas. Our results are the only collision strengths and
effective collision strengths available for this ion. We believe that the
data calculated in this work will be useful in solar, astrophysical and
laser applications. 相似文献
19.
S. Keller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):51-59
Triple differential cross-sections (TDCS) for (
e
,2
e
) processes on C60 have been calculated in the plane wave Born and distorted wave Born approximations using a jellium shell model to describe
the target valence states. The peculiarities of these TDCS are demonstrated by comparison with results for atomic hydrogen.
Ionisation into a resonant state leads to dramatic modifications of the TDCS. This effect could also be observed in a surface
(
e
,2
e
) experiment in specular geometry using a thin film of physisorbed C60.
Received 14 April 2000 and Received in final form 27 July 2000 相似文献
20.
S. Bhattacharya K. B. Choudhury N. C. Deb C. Sinha K. Roy A. Z. Msezane 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(3):335-338
A one channel distorted wave approximation has been used to calculate the ionization cross section for the 3s electron of
Na
atom by alpha particle impact. For a consistency check we have also run the standard CDW-EIS code of McSherry et al. [Comput.
Phys. Commun. 155, 144 (2003)]
and found reasonable agreement in the high energy region among the present results, the CDW-EIS results and the classical
trajectory Monte Carlo (CTMC)
calculations. It is also found that the present
results tend to agree qualitatively with the low energy measurement of Knoop et al. [J. Phys. B 38, 1987 (2005)] at as low as 10 keV amu-1,
although the present theoretical approach is expected to be suitable in the high energy area. This qualitative agreement in
the low energy region is
attributed to the partially correlated ground state wave function used in the present calculation. 相似文献