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1.
Data on the cross sections for single-electron charge exchange and excitation in collisions of He+ ions with C5+, N6+, and O7+ ions in the He+ ion energy range of 0.2–3.0 MeV are obtained for the first time. The cross sections for the single-electron charge transfer
into the singlet and triplet 1snl states of C4+, N5+, and O6+ (2≤n≤5) ions and for the 1s → 2p
0, ±1 electronic excitation of He+(1s) ions are calculated. The calculations were performed by solving close-coupling equations on the basis of ten two-electron
quasi-molecular states. 相似文献
2.
Yu. M. Smirnov 《Optics and Spectroscopy》2012,112(1):50-55
The electron-impact excitation of doublet D-levels of the lutetium atom is studied by the method of extended crossing beams. At the exciting electron energy of 50 eV,
64 excitation cross sections are measured. In the electron energy range of 0–250 eV, nine excitation optical functions are
recorded. The occurrence of perturbations in the spectral series 6s
2(1
S)6p
2
P
12/○ − 6s
2(1
S)nd
2
D
3/2 is discussed. 相似文献
3.
The trielectronic recombination of an In+ (4d
105s
2
1
S
0) ion in collisions with slow electrons, including the two-electron excitation of the 5s2 core of the ion with the simultaneous capture of the triply excited 5p
3 intermediate autoionizing state with its subsequent radiative stabilization 5p
3 → 5s5p
2 + hν has been detected and experimentally examined for the first time. The maximum effective cross section of trielectronic recombination
is 1.6 × 10−16 cm2, which is comparable to the effective cross sections for both dielectronic recombination and electron excitation of the In+ ion. 相似文献
4.
Yu. M. Smirnov 《Journal of Applied Spectroscopy》2007,74(5):613-617
The behavior of excitation cross sections of the strontium atom was studied experimentally in the spectral series 5s4d1D2-5snf1F
3
o
in the range n = 4–26, and also the optical excitation functions for lines in the same series in the range n = 4–12. It was
established that the beginning of the series is perturbed. The effect of the perturbation is manifested both in the irregular
course of the dependence of the absolute values of the cross sections on n, and in the difference between the shapes of the
optical excitation functions for different terms of the series. The results obtained are compared with available experimental
data.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 557–560, September–October, 2007. 相似文献
5.
A. A. Borovik 《Optics and Spectroscopy》2011,110(5):680-685
We study the energy dependences of electron excitation cross sections of the autoionizing levels (5p
56s
2)2
P
3/2 and (5p
55d(3
P)6s)2
P
3/2, as well as the autoionization cross sections of cesium atoms in the impact energy range from the excitation threshold to
600 eV. It is established that an increase in the excitation cross section of the 2
P
3/2 levels (to 60% of the maximum value) and the deep minimum in the autoionization cross section observed in the energy region
of 17–27 eV are caused by the predominance of the radiative decay channel for autoionizing levels with excitation thresholds
above 17 eV. The high efficiency of the process is mainly related to the resonance excitation of these levels in the near-threshold
energy region. 相似文献
6.
G. G. Bohachov 《Optics and Spectroscopy》2011,110(5):672-679
Thallium emission spectra in the 115–300 nm range excited by electron-atom collisions at electron energies of 12–300 eV are
investigated. A number of weak lines that cannot be unidentified using spectroscopic tables are found in the 140–170 nm range.
Two of them (144.9 and 148.0 nm) are attributed to the radiative decay of levels that belong to the 6s6p
2 configuration and that lie above the ionization potential. A weak emission with an excitation threshold of about 9 eV is
revealed in the vicinity of the Tl II resonance line at 132.2 nm. The excitation function of the emission is measured for
electron energies below 15.5 eV. It is found that the emission consists of two lines, which also appear due to the excitation
of the 6s6p
2 configuration and correspond to the radiative decay of levels that are common with the lines at 144.9 and 148.0 nm mentioned
above. Their calculated wavelengths are 130.2 and 132.7 nm, respectively. 相似文献
7.
Electron impact excitation cross sections of argon from the
3p
54s matastable states to the excited
states of 3p
54p configuration were calculated
by using the fully relativistic distorted wave method, based on the multi-configuration
Dirac-Fock (MCDF) theory. The influence of electron correlation effects on cross sections
were discussed in detail. For low energy impact, it is found that the electron correlation
effects have a large influence on the cross sections and make the cross sections smaller.
However, this influence become smaller with the increasing of incident electron energy.
The present results are in good agreement with the experiments of Boffard et al. [Phys.
Rev. A 59, 2749 (1999)] in most cases. 相似文献
8.
Dr. Minakshi L. K. Jha S. N. Chatterjee B. N. Roy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):331-339
H+ and He2+ impact single and double ionization cross
sections of ground state lead atoms have been calculated in the binary
encounter approximation. Calculations of direct double ionization cross
sections have been performed in the modified double binary encounter model.
The accurate expressions of σΔE (cross-section for energy
transfer ΔE) and Hartree-Fock velocity distributions for the target
electrons have been used throughout the calculations. Contributions to
double ionization from Auger effect following ionization of inner shells
have been considered in the present work. Our H+ impact single and
double ionization cross sections are in good agreement with the experimental
observations. In calculations of He2+ impact cross sections, the
present theoretical approach shows limited success in the experimentally
investigated region (50–350 keV amu-1). 相似文献
9.
M. K. Pandey R. K. Dubey D. N. Tripathi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):275-279
The Classical Trajectory Monte Carlo (CTMC) Method has
been used to calculate the differential, partial and total single electron
capture cross sections for the collision of H+/D+ with Ca and Mg
atoms in the energy range of 1–100 keV. The differential cross sections
at angles near the diffraction limit (<0.1○) in both systems
show a forward peak followed by an asymptotic fall at higher angles. Total
and partial capture cross sections are found to be in good agreement with
the experimental observations. Oscillations in the partial capture cross sections have been explained due to the swapping
of the field electron.
Isotope effect in the electron transfer is reported to be negligible. 相似文献
10.
J. Lecointre D. S. Belic S. Cherkani-Hassani P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(3):441-448
Absolute cross sections for electron impact dissociation of ND+ leading to the formation of D+ have been measured by applying the animated electron-ion beam method in the energy range from the reaction threshold up to
2.5 keV. The maximum inclusive cross section is observed to be (16.8 ± 0.8) × 10−17 cm2 at the electron energy of 65.1 eV. The appearance energy for the D+ production is measured to be (4.0 ± 0.5) eV. Collected data are analyzed in details by means of an original procedure in
order to determine separately the contributions of dissociative channels. A specific Monte Carlo modeling has been developed,
which is proven to reconstruct adequately the dissociative ionization cross section. The present energy thresholds provide
information about the ground and excited states of the molecular ion, as well as about the possible population of the vibrational
levels. The reaction D2(v) + N+ (or H2(v) + N+) is a probable source for that population and it constitutes the first step of the molecular activated processes, so the
corresponding chain of reactions has to be considered to study the chemistry of plasma sources. 相似文献
11.
Yu. M. Smirnov 《Optics and Spectroscopy》2010,109(3):330-335
The excitation of odd levels of the thulium atom, spontaneous transitions from which terminate at the 4f
13(2
F
o)6s6p(3
P
o) (7/2, J
2) levels with J
2 = 0, 1, is studied by the method of extended crossing beams. Fifty four excitation cross sections are measured at an excitation
electron energy of 50 eV. Seven optical excitation functions are recorded in the electron energy range of 0–200 eV. 相似文献
12.
M. Ya. Amus’ya A. I. Mikhailov I. A. Mikhailov 《Journal of Experimental and Theoretical Physics》1998,86(2):299-304
Inelastic photon scattering by helium atoms and helium-like ions with simultaneous excitation of the two-electron transition
1s
2→2s
2 is examined in the nonrelativistic energy range I≪ω≪m (I is the ionization potential, ω is the photon energy, m is the electron mass, and ℏ=c=1). The electrons are assumed to be moving in the Coulomb field of the nucleus, and the electron-electron interaction is
taken into account in the lowest perturbation order. The differential and total cross sections of the process and the autoionization
width of the 2s
2 energy level are calculated. The numerical value of the autoionization width is found to agree with the results of the more
rigorous calculations of other researchers.
Zh. éksp. Teor. Fiz. 113, 539–549 (February 1998) 相似文献
13.
Absolute cross sections for single and double electron-impact detachment of the S- ion have been investigated over collision energy ranges of 0-60 eV and 0-30 eV, respectively. The experiment was performed at the ion storage ring, CRYRING. The threshold energies were measured to be 6.6 eV for single detachment and 19.8 eV in the case of double detachment. The single detachment cross section has a maximum of 6.7 x 10-16 cm2 at 30 eV. The double detachment cross section was studied only in the threshold region. No sharp structures were observed in either of the cross sections.Received: 24 April 2003, Published online: 29 July 2003PACS:
34.80.Dp Atomic excitation and ionization by electron impact - 34.80.Kw Electron-ion scattering; excitation and ionization 相似文献
14.
Yu. M. Smirnov 《Optics and Spectroscopy》2010,108(1):23-28
The excitation of transitions from the 2
S
∘, 2
P
∘, and 2
D
∘ levels of the cobalt atom is studied by the method of extended crossing beams. Seventy-six excitation cross sections are
measured at an exciting electron energy of 50 eV. Nine optical excitation functions are recorded in the electron energy region
of 0–200 eV. Possible channels of excitation of levels under study are discussed. 相似文献
15.
M. Gupta K. L. Baluja 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):475-483
Electron-H2S collision process is studied using the R-matrix method. Nine low-lying states of H2S molecule are considered in the R-matrix formalism to obtain elastic integral, differential, momentum transfer and excitation cross sections for this scattering
system. We have represented our target states using configuration interaction (CI) wavefunctions. We obtained adequate representation
of vertical spectrum of the target states included in the scattering calculations. The cross sections are compared with the
experiment and other theoretical results. We have obtained good agreement for elastic and momentum transfer cross sections
with experiment for entire energy range considered. The differential cross sections are in excellent agreement with experiment
in the range 3–15 eV. A prominent feature of this calculation is the detection of a shape resonance in 2B2 symmetry which decays via dissociative electron attachment (DEA). Born correction is applied for the elastic and dipole allowed
transition to account for higher partial waves excluded in the R-matrix calculation. The electron energy range is 0.025–15 eV. 相似文献
16.
The transition energies, wavelengths and dipole oscillator strengths of 1s22p—1s2
nd (3⩽n⩽9) for Mn22+ ion are calculated. The fine structure splittings of 1s2
nd (n</9) states for this ion are also evaluated. In calculating energy, the higher-order relativistic contribution is estimated
under a hydrogenic approximation. The quantum defect of Rydberg series 1s2
nd is determined according to the quantum defect theory. The results obtained in this paper excellently agree with the experimental
data available in literatures.
Supported by the National Natural Science Foundation of China (Grant No. 10774063) 相似文献
17.
E.Ya. Paryev 《The European Physical Journal A - Hadrons and Nuclei》2000,7(1):127-137
The inclusive K+ meson production in photon–induced reactions in the near threshold and subthreshold energy regimes is analyzed with respect
to the one–step (γN→K
+
Y, Y=Λ,Σ) incoherent production processes on the basis of an appropriate new folding model, which takes properly into account
the struck target nucleon removal energy and internal momentum distribution (nucleon spectral function), extracted from recent
quasielastic electron scattering experiments and from many–body calculations with realistic models of the NN interaction.
Simple parametrizations for the total and differential cross sections of the K+ production in photon–nucleon collisions are presented. Comparison of the model calculations of the K+ differential cross sections for the reaction γ+C12 in the threshold region with the existing experimental data is given, that displays the contributions to the K+ production at considered incident energies coming from the use of the single–particle part as well as high momentum and high
removal energy part of the nucleon spectral function. Detailed predictions for the K+ total and differential cross sections from γH2, γC12 and γPb208 reactions at subthreshold and near threshold energies are provided. The influence of the uncertainties in the elementary
K+ production cross sections on the K+ yield is explored.
Received: 12 April 1999 / Revised version: 11 September 1999 相似文献
18.
A. A. Borovik 《Optics and Spectroscopy》2010,109(3):319-324
We measure the full autoionization cross section of lithium atoms excited by electrons in the energy range from the first
autoionization threshold at 56.39 to 600 eV. Data are obtained by determining the total intensity of electron spectrum of
autoionization states 1sn
1
l
1
n
2
l
2 detected at the “magic” observation angle of 54.7°. The cross section behavior is characterized by a sharp increase to a
maximum value of 1.7 × 10−18 cm2 in the energy interval of 56.4–60 eV and a subsequent monotonic drop to a value of 10−18 cm2 at 600 eV. We have discovered a “thin” cross section structure that reflects the presence of strong resonances of Li− ions in the near-threshold area of excitation of the lowest energy autoionization states (1s2s2)2S, (1s2s2p)4
P, 1s(2s2p
3
P)2
P), and 1s(2s2p
1
P)2
P. We have established that the contribution of autoionization to the absolute cross section of single ionization of lithium
atoms does not exceed 4%. We perform a comparative analysis of the data with analogous data for potassium and cesium atoms. 相似文献
19.
R. A. Fedorko T. A. Snegurskaya N. A. Margitich I. I. Shafranyosh 《Optics and Spectroscopy》2010,109(3):325-329
By means of the optical method using the technique of crossed electron and atomic beams, we obtained the absolute values of
the excitation cross sections of metastable cadmium atoms and their energy dependences. The absolute cross section values
reach ∼10−16 cm2 (at 30 eV). Sharp resonance-like maxima are observed in the energy dependences of the excitation cross section near the excitation
thresholds, which are supposedly related to the formation and decay of negative-ion excited states of. 相似文献
20.
K. Chakrabarti J. Tennyson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(1):31
The R-matrix method is used to study electron collisions with the BeH+
molecular ion. The diatomic version of the UK Molecular R-matrix codes is used and a
configuration-interaction calculation is first performed for the BeH+ target to
obtain its potential energy curves for 19 lowest singlet and triplet states. Scattering
calculations are then done to yield excitation and rotational excitation cross sections in
the energy range 0 − 14 eV. Additionally we also obtain bound states of BeH and their
quantum defects at the BeH equilibrium bond length 2.5369a
0.
Resonance positions and widths for Feshbach resonances in the e-BeH+ system are
also obtained and presented at the equilibrium bond length
2.5369a
0. 相似文献