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1.
《X射线光谱测定》2003,32(4):285-298
The experimental values of L x‐ray fluorescence (XRF) cross‐sections are not available for all the elements in the range La–U, at all the photon energies E in the range EL1 ≤ E ≤ EK. To generate L XRF cross‐sections, where experimental measurements are not available, two empirical relations have been developed, one between the L XRF cross‐sections and photon energy and the other between the L XRF cross‐sections and atomic number. For the measured data on L XRF cross‐sections at incident energies between Ll and K edges of an element and the data on L XRF cross‐sections for elements in the range 57 ≤ Z ≤ 92 at an energy value, polynomial fits have been derived. The L XRF cross‐section values generated with the derived empirical relations were found to be in agreement with the experimental values within their experimental uncertainties. Subsequently, a software code IGELCS was developed to interpolate and to generate the cross‐sections at inter‐energies and for inter‐elements in a single computer run. The running of the software requires minimum input data on five elements at five common energies. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
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
3.
V. V. Afrosimov A. A. Basalaev Yu. G. Morozov M. N. Panov O. V. Smirnov E. A. Tropp 《Technical Physics》2011,56(5):597-604
Time-of-flight mass spectroscopy methods are employed for studying processes occurring during capture of electrons by 3He2+ and Ar6+ multiply charged ions with energy 6z keV (z is the ion charge) from C2H
n
molecules (n = 2, 4, 6) with different multiplicities of C-C bonds. Fragmentation schemes of the molecular ions formed in such processes
are established from analysis of correlations of recording times for all fragment ions. The absolute values of the cross sections
of capture of an electron and capture with ionization are measured, as well as the cross sections of formation of fragment
ions in these processes. The absolute values of total capture cross sections for several electrons are determined. 相似文献
4.
S. Kumari S. N. Chatterjee L. K. Jha B. N. Roy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(2):355-363
H+ impact single and He2+ impact single and double electron
capture cross sections of magnesium atoms have been calculated in the
modified binary encounter approximation (BEA). The accurate expressions of
ion impact sDE\sigma _{\Delta {E}} (cross section for energy transfer
DE\Delta E) and Hartree-Fock momentum distributions of the target
electrons have been used throughout the calculations. On the basis of the
present work it is concluded that inner shell captures by H+ and
He2+ ions incident on magnesium atoms contribute partly to single
electron capture and partly to transfer ionization cross sections. The
calculated He2+ impact double electron capture cross sections of
magnesium are in reasonably good agreement with the experimental
observations. This indicates the success of the present theoretical approach
in study of charge transfer cross sections of atoms as indirect mechanisms do
not interfere with double electron capture processes in this case. 相似文献
5.
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
6.
L. Sharma R. Srivastava A. D. Stauffer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,62(3):399-403
We have used our relativistic distorted-wave method to calculate cross sections for the
electron-impact excitation of the ground state of xenon to all the
5p
57p fine-structure levels. The results
are compared with the recent experimental measurements of Jung et al. [Phys. Rev. A
80, 062708 (2009)]. Analytic fits to our cross sections are also provided
for use in plasma modeling studies. 相似文献
7.
In order to evaluate g
0, the interaction strength of a pair of 52Cr atoms with total spin S = 0, a specially designed s-wave scattering of the pair has been studied theoretically. Both the incident atom and the target
atom trapped by a potential are polarized previously but in reverse directions. Due to spin-flips, the outgoing atom may have
spin component μ ranging from −3 to 3. The outgoing channels are classified by μ. The effect of g
0 on the s-wave cross sections of each of these μ- channels has been predicted. In particular, when the parameters of the trapping potential are given around their optimal
values so that the cross sections can be maximized, distinguished features of the dependence of the cross sections on g
0 are found. These features are helpful for evaluating g
0. 相似文献
8.
9.
B. H. Yanga P. C. Stancil 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(3):317-324
Quantum close-coupling and coupled-state approximation scattering calculations for rotational energy transfer of rotationally
excited CH4 due to collisions with He are presented for collision energies between 10−7 and 3000 cm−1 using the MP4 potential of Calderoni et al. [J. Chem. Phys. 121, 8261 (2004)]. State-to-state cross sections and rate coefficients
from selected initial rotational states of CH4 in symmetries A, E, and F are studied from the ultra-cold to the thermal regime. Comparison of the cross sections with available theoretical results
and experimental data show good agreement. Applications to astrophysics and cold laboratory environments are briefly addressed. 相似文献
10.
Using an elaborate partial fractioning procedure of all 4-parton matrix elements we calculate 3-jet cross sections in e+e− annihilation with mass-cut jet resolution. All subleading contributions from nonsingular terms are included. We give thrust distributions for O(αs2) 3- and 4-jets. We study integrated cross sections as a function of the cutoff and check the reconstruction of O(αs2) σtot using recently calculated 2-jet cross sections with the same partial fractioning of 4-parton terms. 相似文献
11.
G. H. Hovhannisyan A. S. Danagulyan A. R. Balabekyan J. Adam V. G. Kalinnikov V. S. Pronskikh A. A. Solnyshkin V. M. Tsoupko-Sitnikov N. M. Vladimirova 《Physics of Atomic Nuclei》2012,75(2):125-135
The formation cross sections for about 110 products of interaction between a 12C ion beam of energy 2.2 GeV per nucleon and tin targets from the isotopes 112,118,120,124Sn were calculated. Massyield and charge distributions were obtained for 112,118,124Sn targets. An analysis of these charge distributions reveals that the positions of their maxima, Z
p
, are different for targets having different nucleon compositions. The formation cross sections for neutron-rich products
originating from neutron-rich targets are found to increase in all product-mass regions considered in our study. Mass distributions
are compared for proton-, deuteron- and ion-nucleus reactions. 相似文献
12.
Coulomb deexcitation differential cross sections of excited muonic hydrogen in collisions with the hydrogen atom are studied
for the first time. In the fully quantum-mechanical close-coupling approach, both the differential cross sections for the
nl → n′l′ transitions and l-averaged differential cross sections have been calculated for the initial exotic atom states with n = 2–6 at kinetic energies of E
cm = 0.01–15 eV and for scattering angles of ϑcm = 0°–180°. The vacuum polarization shifts of the ns states are taken into account. The differential cross sections of the elastic and Stark scattering obtained in the same approach
are also presented. The main features of the calculated differential cross sections are discussed, and a strong anisotropy
of Coulomb deexcitation cross sections is predicted.
The text was submitted by the authors in English. 相似文献
13.
Experimental ionization cross sections for K‐shell by protons in target atoms from beryllium to uranium available in the literature from 1953 to 1999 (nearly 5400 values) are collected to deduce the semi‐empirical K‐shell ionization cross sections by fitting the experimental data normalized to their corresponding theoretical values based on the ECPSSR model which accounts for Coulomb deflection, Energy loss of the projectile, Perturbed Stationary State and Relativistic effects, as a function of the reduced velocity parameter. Our results are compared with the experimental data and with the ECPSSR values and reference ionization cross sections obtained by Paul and Sacher [H. Paul and J. Sacher, At. Data. Nucl. Data. Tables 1989 , 42, 105]. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
14.
Swapan Das 《Physics of Atomic Nuclei》2011,74(1):40-48
The strong coupling of rho meson to the nucleon produces s- and p-wave rho-meson-nucleon (ρN) resonances. In a nucleus, the ρN-resonance-hole polarization generates the optical potential or self-energy for the ρ meson. The scattering of ρ meson due to this potential provides valuable information about the ρN-resonance dynamics in a nucleus. To investigate it, we use this potential to calculate the mass distribution spectrumfor
the ρ meson produced coherently in the proton-nucleus reaction. The cross sections arising due to s- and ρ-wave ρN resonances have been presented. The coherent and incoherent contributions to the cross sections due to these resonances are
compared. In addition, the calculated results due to nonrelativistic and relativistic ρ-meson self-energy are illustrated. 相似文献
15.
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
16.
J. Lecointre H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(2):331-345
Absolute cross sections for electron-impact single ionization, dissociative
excitation and dissociative ionization of the ethynyl radical ion
(C2D+)^+) have been measured for electron energies ranging from the
corresponding reaction thresholds to 2.5 keV. The animated crossed
electron-ion beam experiment is used and results have been obtained for the
production of C2D2+, C2+, C2+_2^+ , CD+, C+ and
D+. The maximum of the cross section for single ionization is found to
be (2.01 ± 0.02) × 10-17 cm2, at the incident electron
energy of 105 eV. Absolute total cross sections for the various singly
charged fragments production are observed to decrease by a factor of almost
three, from the largest cross-section measured for C+, over C2+_2^+
and CD+ down to that of D+. The maxima of the cross sections are
obtained to be (14.5 ± 0.5) × 10-17 cm2 for C2+_2^+,
(12.1 ± 0.1) × 10-17 cm2 for CD+, (27.7 ±
0.2) × 10-17 cm2 for C+ and (11.1 ± 0.8) × 10-17 cm2 for D+.
The smallest cross section is measured to
be (1.50 ± 0.04) × 10-18 cm2 for the production of the
doubly charged ion C2+. Individual contributions for dissociative
excitation and dissociative ionization are determined for each
singly-charged product. The cross sections are presented in closed analytic
forms convenient for implementation in plasma simulation codes. Kinetic
energy release distributions of dissociation fragments are seen to extend
from 0 to 6 eV for the heaviest fragment C2+_2^+, up to 11.0 eV for
CD+, 14.2 eV for C+ and 11.2 eV for D+ products. 相似文献
17.
G. H. Hovhannisyan A. S. Danagulyan A. R. Balabekyan N. A. Demekhina J. Adam V. G. Kalinnikov V. S. Pronskikh 《Physics of Atomic Nuclei》2012,75(2):136-142
Cross sections for charge-exchange reactions induced by the interaction between 12C ions of energy E12 C = 2.2E_{^{12} C} = 2.2 GeV per nucleon and tin targets enriched in the isotopes 118,120,124Sn were measured by the induced-activity method. The cross sections for products whose charge numbers were in excess of the
target charge number (Sb and Te) were determined. The shape of the isotope distribution of Sb products was indicative of the
evaporative character of neutron emission in the formation of final-state products. The dependence of cross sections for charge-exchange
reactions on the nucleonic composition of the target was considered. The contribution of electromagnetic excitation to the
cross section for the reaction 124Sn(12C, x)124Sn was estimated. 相似文献
18.
Synchrotron radiation induced X‐ray production cross sections of 66Dy at energies across its Li (i = 1–3) subshell absorption edges
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The X‐ray production (XRP) cross sections for the 66Dy Lk (k = l, α, η, β2,6,7,15, β1,6, β1,3,4,6, β2,7,15, γ1,5, γ2,3) emission lines have been measured by tuning the incident synchrotron radiation at energies over the range 7.8–9.2 keV and ~10–370 eV above the respective Li (i = 1–3) absorption edges. These measurements aim to check the reliability of the independent particle approximation models used to generate the theoretical data sets of different physical parameters required to calculate the XRP cross sections and also investigate the influence of many body effects on the photoionization process. The measured values have been compared with 4 sets of XRP cross sections calculated using the Dirac–Fock model‐based X‐ray emission rates, 2 sets of the Li (i = 1–3) subshell photoionization cross sections deduced from the self‐consistent Dirac–Hartree–Fock model‐based values and the nonrelativistic Hartree–Fock–Slater model‐based values, and 2 sets of the fluorescence (ωi) and Coster–Kronig (fij) yields. The present measured Lγ2,3 (originating from decay of the L1 subshell vacancies) XRP cross sections are found to be significantly higher than different sets of theoretical values, whereas a good agreement is generally observed for the various other XRP cross sections and relative intensities. 相似文献
19.
M. A. Zhusupov A. Yu. Zaikin E. T. Ibraeva Sh. Sh. Sagindykov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(7):1013-1018
The differential cross sections of proton elastic scattering from 8Li and 9Li nuclei in inverse kinematics have been calculated. The cross sections were determined within the Glauber diffraction theory
with the wave functions of nuclei in the three-particle α-t-n, α-t-2n, and 7Li-n-n models. Comparison with the existing experimental data for E = 700 and 60 MeV/nucleon made it possible to draw a conclusion about the quality of the wave functions and the adequacy of
the potentials used for their calculations. 相似文献
20.
We report calculated total elastic cross sections Qel, total ionisation cross sections, Qion, summed total excitation cross sections ∑Qexc and total cross sections QT for CH3SH upon electron impact for energies from ionisation threshold to 5 keV. We have employed Spherical Complex Optical Potential (SCOP) formalism to calculate total elastic cross section Qel, and total inelastic cross section Qinel and used Complex Scattering Potential – the ionisation contribution (CSP-ic) method to extract the ionisation cross sections, Qion, from the calculated Qinel. The calculated total cross sections are examined as functions of incident electron energy and are compared with available data wherever possible and overall good agreement is observed. In this work Qel, Qion, and ∑Qexc are reported for the first time for CH3SH in this energy range. 相似文献