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1.
Electron impact double ionization cross-sections for Ba and Ba+ have been calculated in the binary encounter approximation. Hartree-Fock velocity distribution has been used for the first
ejected electron and a hydrogenic velocity distribution for the second. For Ba+ the focusing effects of the target ion on the incident electron have been incorporated in the calculations. Contributions
from ionization-autoionization to the ionization cross-sections, as observed in experiments, have been included in the present
work. The calculated results show structures as observed in recent experiments. 相似文献
2.
The binary encounter approximation has been used for calculations of electron impact single ionization cross-sections for
F, Cl, Br and I and double ionization cross-sections for Br and I. Contributions of ionization from inner shells have also
been included in the calculations. Hartree-Fock momentum distribution has been used for the bound electron as far as possible.
The results have been found to be in satisfactory agreement with experimental observations. 相似文献
3.
M-shell ionization cross sections for atoms due to the impact of proton and α-particles have been calculated in the binary
encounter approximation. The effects of Coulomb deflection of the incident projectile and increase in binding of the target
electron have been investigated. Roothan-Hartree-Fock velocity distribution for the target electrons has been used in the
present work. The calculated cross-sections have been compared with experimental results and other theoretical calculations
wherever available. The present calculations give a good account of experimental observations. 相似文献
4.
Alpha particle and deuteron impactL-subshell ionization cross-sections of Ar, Cu, Ge, Br, Zr and Ag have been computed using Vriens’ expressions for ionization
cross-section of atoms due to impact of heavy charged particles. The effects of Coulomb deflection of the projectile and increase
in binding of the target electron in the presence of projectile have been incorporated. Hartree-Fock velocity distributions
for the target electrons have been used in the present calculations. The simple binary encounter approximation model is found
to give results which are in satisfactory agreement with those obtained from experiments and from other theories. 相似文献
5.
The binary encounter approximation has been used to investigate the effect of charge state of the target atom (ion) on the
electron impact excitation autoionization cross-sections. Roothan-Hartree-Fock (RHF) velocity distribution for the bound electrons
has been used through-out the calculations. The present results give a good account of the experimental observations. 相似文献
6.
L-shell ionization cross sections of Nb by electron impact in the energy range from 3 to 40 keV have been determined with a Si(Li) X-ray detector. Influence of reflected electrons from backing on the measurement was corrected using an electron transport model. The experimental results are compared with theoretical calculations of Gryzinski and McGuire. 相似文献
7.
The applicability of a combined open-shell Hartree-Fock theory of atomic-molecular and nuclear systems to the states of a single configuration which has the arbitrary symmetry of open shells is explicitly demonstrated by calculations based on the combined Hartree-Fock-Roothaan equations for atoms. As examples of an application of the combined theory using single-zeta Slater-type basis sets, the calculations have been performed for the lowest states of the lowest and excited electronic configurations of carbon and nitrogen atoms containing one-, two- and three-open shells. For the case of single-open shells for carbon and nitrogen atoms, the double-zeta basis-set calculations are also presented. The results of computer calculations for the orbitals, kinetic and total energies, linear combination coefficients and virial ratios are given. 相似文献
8.
Electron impact single and double ionization cross sections of gallium have been calculated in the binary encounter approximation
using accurate expression for σΔ;E including exchange and interference as given by Vriens and Hartree-Fock velocity distributions for the target electrons throughout
the calculations. It is concluded that the ionization of 3d shell contributes partly to single ionization and partly to double
ionization. The results so obtained show reasonably good agreement with the experimental data. 相似文献
9.
S. S. Moliver 《Physics of the Solid State》2000,42(4):673-682
The restricted Hartree-Fock-Roothaan method with closed and open electronic shells projected by electron density matrices and the quasi-molecular large-unit-cell (LUC) model have been applied to calculate the electronic structure of monovacancy and semivacancy in the neutral charge state in the totally symmetric atomic configuration with relaxation and symmetry-lowering distortions. The difference in the energies of states with total spins of 1 and 3/2 for a neutral monovacancy is determined within the ΔSCF approximation. 相似文献
10.
测量了入射离子能量为27 keV、45 keV和66 keV时Ar3 Ar碰撞反应各子过程的分截面,通过将其归一化到Bliman,Dousson等人所测量的截面值,获得了绝对截面.结果表明,该能区电子俘获过程仍占主导地位,但转移电离过程已不能忽略.结果还表明,各子过程反应截面基本不随能量变化.与考虑自电离的MCBM(Molecular Coulombic overBarrier Model)模型比较发现,模型所给截面普遍高于实验测量值,这在一定程度上是由于归一化时带来的系统误差.在误差允许的范围内,单电子和双电子俘获截面符合的比较好,但三电子俘获截面却相差一个数量级.对于实验观测到的转移电离过程,模型却预言并没有此过程发生. 相似文献
11.
12.
L-shell partial production cross sections of Lα-, Lβ-, Lγ- rays by electron impact were measured by observing the counts of X-ray from impacted thin tungsten target. Total production cross sections and mean ionization cross sections were deduced from these measured results. The electron beam energy range was from 11 to 36 keV. Tungsten was sputtered onto a carbon backing to reduce bremsstrahlung of the backing. The effect of electrons reflected by the backing has been corrected. Comparison with two theoretical calculations has performed. The experimental results agree rather well with the theoretical predications. 相似文献
13.
利用最新发展起来的适用于低能电子入射的反应显微成像谱仪,对电子轰击He原子近阈值的双电离过程进行了研究,实验测量了反应后4个粒子的全部动量,获得了五重微分截面及出射粒子间的关联信息.着重分析了在入射电子束与出射电子构成的平面内,3个均分系统剩余能量的电子出射角关联关系,并与理论计算进行了比较.研究表明,当两个电子反向出射时,第3个电子垂直于这两个电子动量方向出射的几率最大.在1个电子垂直于平面出射时,通过理论计算结果与平面内出射角分布的比较,发现DS6C理论能够较好地描述实验结果. 相似文献
14.
The ionization level and free electron density of most abundant elements (C,
N, O, Mg, Al, Si, S, and Fe) in the sun are calculated from the centre of
the sun to the surface of the photosphere. The model and computations are
made under the assumption of local thermodynamic equilibrium (LTE). The
Saha equation has been used to calculate the ionization level of
elements and the
electron density. Temperature values for calculations along the solar
radius are taken from references. 相似文献
15.
16.
The Hartree-Fock-Roothaan ab initio self-consistent average field method has been used in calculating the pair interaction
potentials for atoms in the P2 and GaP molecules. The gallium and phosphorus atoms are considered in their ground states. The calculations agree well with
experiment.
Voronezh State Technical University, Voronezh. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No.
1, pp. 95–99, January, 1999. 相似文献
17.
基于处理裸核离子与中性原子碰撞电离过程的OBKN和ECPSSR理论模型,系统计算了不同裸核离子与中性原子碰撞K壳层电子俘获截面和直接电离截面,并与其它文献已有的理论和实验结果进行了比较.研究结果表明:碰撞能量较低时,电子俘获截面大于直接电离截面,随着碰撞能量的增加,电子俘获截面和直接电离截面均是先增大后减小且直接电离截面减小地非常缓慢,高能时,直接电离截面大于电子俘获截面.当入射炮弹离子速度接近0.67倍靶原子K壳层电子速度时,电子俘获截面达到最大值,而当入射炮弹离子速度接近靶原子K壳层电子速度时,直接电离截面达到最大值. 相似文献
18.
基于处理裸核离子与中性原子碰撞电离过程的OBKN和ECPSSR理论模型,系统计算了不同裸核离子与中性原子碰撞K壳层电子俘获截面和直接电离截面,并与其它文献已有的理论和实验结果进行了比较.研究结果表明:碰撞能量较低时,电子俘获截面大于直接电离截面,随着碰撞能量的增加,电子俘获截面和直接电离截面均是先增大后减小且直接电离截面减小地非常缓慢,高能时,直接电离截面大于电子俘获截面.当入射炮弹离子速度接近0.67倍靶原子K壳层电子速度时,电子俘获截面达到最大值,而当入射炮弹离子速度接近靶原子K壳层电子速度时,直接电离截面达到最大值. 相似文献
19.
Electron-induced Hf-, W-L-shell partial, total production cross sections, mean ionization cross sections and Hf-L_3-shell ionization cross sections (at two energies) have been measured as functions of electron energies (from near threshold to 36keV). The influence of electrons reflected from the backing of the thin targets on measured results was corrected using a model to relate to the electron transport process. The mean paths of electron multi-scattered in the target itself (including forward and backward scattering) were calculated by means of Monte Carlo program (EGS4) and they were used to correct measured results. A comparison with both theoretical predictions was given. 相似文献
20.
The cross section for electron positron pair production in non relativistic collisions of protons with heavy nuclei has been calculated. Extending previous calculations, the Coulomb distortion of electron, positron, and projectile wave functions in the target field has been taken into account. Former discrepancies between calculation and experimental results have been removed. 相似文献