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1.
A distorted-wave Born exchange (DWBE) approximation including relativistic correction is used to calculate the electron-impact ionization cross sections and rate coefficients for the highly charged ions Ar7+,…,Ar17+. The comparison of the calculated results with the experimental data and other theoretical calculations shows that the DWBE method is valid for these ions of argon. The calculated results for direct ionization cross sections and excitation autoionization were fitted by empirical formulas to meet the requirements of applications. A set of improved empirical formulas are used for the fast and accurate calculations of rate coefficients from the fit parameters of cross sections.  相似文献   

2.
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   

3.
Fragmentation accompanying the loss of electrons by butane and isobutane (C4H10) molecules in collisions with energy H+, He2+, and Ar6+ ions of kiloelectronvolt energies is studied. The electron density functional technique is applied to C n H2n+2 alkane molecules and their respective C n H 2n+2 + ions to carry out quantum-chemical calculations of the atomic spacing, electron total energy for the initial configuration of the ionizing molecules and ions in the ground state, and atomic bond breaking energy necessary to produce different ion fragments. The fragmentation energy is correlated with the fragmentation probability. It is shown that the relative cross sections of ion fragmentation depend primarily on the related energy consumption. However, the process cross section is also strongly affected by the initial configuration of C4H10 isomer molecules, as well as by the amount of dangling and arising atomic bonds involved in the formation of each ion fragment.  相似文献   

4.
类氦离子的KLL双电子复合过程的相对论理论研究   总被引:3,自引:0,他引:3       下载免费PDF全文
在相对论多组态Dirac-Fock理论基础上,发展了计算双电子复合截面的程序.并以类锂C3+,Ar15+,Kr33+和U89+等离子为例,详细计算了共振双激发态1s2l2l′的辐射衰变率、Auger衰变率及相应的双电子复合截面.对于C4+,Arl6+和Kr34+离子的结果与已有的计算和实验结果都能很好地符合;对于U90+离子,则重点 关键词: 双电子复合 截面 MCDF  相似文献   

5.
杨宁选  蒋军  颉录有  董晨钟 《物理学报》2008,57(5):2888-2894
利用新近发展的基于全相对论扭曲波方法研究电子-离子碰撞激发过程的计算程序,通过对Breit相互作用的考虑,计算了类氦等电子序列离子从亚稳态1s2s3S1激发2s电子到n=2,3壳层的电子碰撞激发截面;研究了不同入射电子能量时Breit相互作用对碰撞激发截面的影响,进一步总结了沿等电子序列变化时,Breit相互作用对截面影响的一般规律.部分计算结果与实验结果进行了比较,得到了很好的一致性. 关键词: 全相对论扭曲波方法 Breit相互作用 电子碰撞激发截面  相似文献   

6.
The subject of investigation is the fragmentation of variously charged molecular ions arising in col-lisions of several kiloelectronvolt H+, He2+, and Ar6+ ions with molecules of the simplest alkanes (from methane to butane). Using the method of time-of-flight mass spectrometry, the formation cross sections of dissociation-induced fragment ions are measured. The dissociation takes place when an incident ion captures an electron from a methane, ethane, or propane molecule. The role of additional ionization of the molecule, which accompanies the electron capture by the incident ion, is elucidated. The kinetic energy spectrum for protons resulting from the fragmentation of multiply charged alkane ions is determined. The most plausible kinetic energies of protons depending on the degree of ionization and molecule size fall into the range 1–25 eV. It is shown that, when the molecule loses several electrons, the kinetic energies of protons are governed by Coulomb interaction between all fragment ions and are determined by their flying apart from the relative spatial arrangement of corresponding atoms in a parent molecule.  相似文献   

7.
The photoionization cross sections for the 4p shell of ions of the Kr isoelectronic sequence Rb+, Sr2+, and Y3+ are calculated. The configuration interaction theory and the perturbation theory are used to describe the many-electron effects. The relativistic effects are taken into account in the Pauli-Fock approximation. The calculated resonance structure of photoionization cross sections for the 4p shell in the region below the 4s threshold associated with the autoionization of the 4s-np singly excited states and the 4p4p-nln′l′ doubly excited states reproduces the results of recent measurements of total photoabsorption cross sections for the Rb+, Sr2+, and Y3+ ions. It is found that, as the nuclear charge in the isoelectronic sequence increases, the ratio between the direct and correlation parts of amplitudes of the 4s-(n/?)p transition changes and, as the consequence, the minimum of the photoionization cross section of the 4s shell shifts from the continuous spectrum to the region of states of discrete spectrum. This accounts for the strong changes in the shape of the 4s-np resonances in the photoionization cross sections for the 4p shell of Rb+, Sr2+, and Y3+, as well as the distinction between the shapes of the 4s-6p 1/2 mirror resonance in the partial 4p 1/2 and 4p 3/2 photoionization cross sections for the Y3+ ion which do not suppress each other in the total photoionization cross section, as is the case for similar resonances in Rb+ and Sr2+.  相似文献   

8.
The cross sections of the detachment of one and two electrons during the collision of two negative ions H? + H?, H? + Cs?, and Cs? + Cs? are calculated in a wide range of collision energies: from the energy threshold to approximately 100 keV. In adiabatically slow collisions, the detachment of electrons occurs as a result of one-or two-electron Auger decays whose rates are calculated in the approximation of asymptotically large separations between ions. For high collision energies, the cross sections of the electron detachment are calculated by the method of close coupling of states. The calculated cross sections are in good agreement with the results of experimental measurements made for the H? + H? collision.  相似文献   

9.
颉录有  张志远  董晨钟  蒋军 《物理学报》2008,57(10):6249-6258
利用相对论扭曲波方法和新发展的研究电子碰撞激发过程的计算程序REIE06,系统计算了电子碰撞激发高离化态类镍Gd36+和Rn58+—U64+(Z=86—92)离子从基态到4l(l=s,p,d,f)次壳层精细结构能级的碰撞强度和截面.研究了随等电子系列变化时,从基态到与X射线激光有关的3d94p和3d94d激发态能级的电子碰撞激发截面随Z的变化,讨论了强的组态相互作用对高离化态类镍离子截面的影响.通过对Gd36+离子涉及X射线激光跃迁的相关能级电子碰撞激发速率系数的计算,分析了等离子体中电子温度对碰撞过程的影响.同时,目前部分计算结果与以往的理论结果进行了比较,得到了很好的一致性. 关键词: 电子碰撞激发 相对论扭曲波方法 高离化态类镍离子  相似文献   

10.
本文给出了单、双电荷离子和He,Ne,Ar,碰撞过程中产生的激发态的实验结果。Heq+,Arq+(q=1,2)离子束实验室能量为(70—170)×q keV。光学测量由光学多道分析系统(OMA)完成,波长范围为200—800nm。观察到单、双电荷离子和原子碰撞中各种不同的激发过程,讨论了发射截面和入射离子电荷数、势能亏损的依赖关系。 关键词:  相似文献   

11.
Recombination of multiply charged ions with electrons at very low relative energies has become a major topic of interest, due to the observation of rates which are enhanced beyond the expectations for radiative recombination. We present results for Ar16+ and Ar18+ ions from systematic measurements along the argon isonuclear sequence using a high density cold electron beam target (ne = 7 × 109 cm-3) at the UNILAC of GSI. The transverse and longitudinal temperatures of the electron beam were determined from DR resonance features observed with metastable Ar16+ (23S) ions. The rate at Erel = 0 for radiative recombination of completely stripped Ar18+ calculated with electron beam temperatures kT = 0.002 eV, kT = 0.2 eV amounts to α = 10-9 cm3 s-1. This is exceeded by nearly a factor of 10 by the rate measured in experiments with Ar18+ ions. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

12.
对Ar2+与Li,Na碰撞过程中由于单电子俘获而产生的ArII谱线进行了绝对测量,给出各谱线的发射截面数据。入射离子能量为40—300keV。从发射截面对势能亏损的依赖关系,发现对应中等△E(>0)值的过程具有较大的截面。并且还发现与观察到的光谱线相应的激发态属于一个电子组态中高J量子数的态。 关键词:  相似文献   

13.
The absolute values and the shape of the double differential cross sections of the resonance inelastic scattering of a linearly polarized x-ray photon in the energy region of the ionization threshold of the deep 1s shell of the Ne atom and the Si4+ and Ar8+ neon-like ions are calculated in the nonrelativistic approximation for the wave functions of one-electron states and in the dipole approximation for the scattering probability amplitude. The multiparticle effects of radial relaxation of electronic shells in the field of a deep vacancy and of stabilization of the deep vacancy as a neutral atom transforms to a multiply charged positive ion, as well as the effect of the spin-orbit splitting of the 2p valence shell, are taken into account. The calculation results are predictive in character.  相似文献   

14.
At collision energies below 15 keV total charge transfer cross sections have been measured for multiply charged Arζ+(2≦ζ≦6) and Neζ+(2≦ζ≦4) ions colliding with atomic hydrogen. A Wood discharge was used to provide a hydrogen target with a sufficiently high degree of dissociation. Results are compared with measurements performed at higher energies and with theoretical calculations. For ζ=2 cross sections in atomic hydrogen are much smaller than in the molecular case, for ζ>2 the ratio of these cross sections varies between 0.7 and 1.6.  相似文献   

15.
In the energy range 2.4 to 33.3 eVCM, relative cross sections have been measured forL α emission from impact of Ar+ ions in a beam on a H2 gas target. Absolute cross sections, obtained by normalization to literature data, are 1–10×10?16cm2 for metastable Ar+ and 1–20×10?18cm2 for ground state Ar+. In the former case, the dominant mechanism is probably dissociative electronic energy transfer, while in the latter case dissociative charge transfer is the most likely process. In addition, at the lowest energiesL α resulting from a chemiluminescent rearrangement Ar++H2→ArH++H(2p) has been observed.  相似文献   

16.
Doubly charged negative ions formed when electrons with controlled energies interact with isolated fluorinated fullerene molecules C60F n (n = 36, 48) have been detected and investigated by resonant electron capture mass spectrometry. The dependence of the intensity of the formation of doubly charged negative ions of fluorofullerenes on the energy of attached electrons has been measured. An original method, which is based on the experimental data and does not require additional calibration quantities, has been developed for estimating the absolute cross section for the formation of doubly charged negative ions. The absolute cross sections for the formation of the most intensely formed ions C60F 36 2? and C60F 48 2? are estimated to be about 1.1 × 10?24 and 1.5 × 10?24 m2 at their maximum-yield energies of 2.0 and 1.6 eV, respectively.  相似文献   

17.
18.
The characteristic angles and cross sections for a (\mathop 1- 0) + (\mathop 1- 1)(\mathop 1\limits^ - 0) + (\mathop 1\limits^ - 1) reaction in which H atoms with an energy of 0.1–10 000 MeV lose electrons when scattered on C, N, or O atoms were calculated for the relativistic case of the Bethe scattering theory. The cross sections for N2, O2, and CO2 molecular targets were obtained using the additivity rule. The results presented are compared with known experimental and theoretical data.  相似文献   

19.
The cross sections for the transitions between the components of the fine structure of triplet levels with n = 2 and 3 in He and He-like ions colliding with protons have been considered. The feature of the problem is the presence of a virtual level coupled with the components of the multiplet by dipole-allowed transitions. As a result, the cross section at intermediate collision velocities has a peak, which is sometimes much higher than the cross section for the transition induced by collisions with electrons. The cross sections for He and C4+ and Fe24+ ions have been calculated by the tight-binding method.  相似文献   

20.
The problem of ionization of ions in ion-ion and ion-neutral relativistic collisions is considered. Formulas for ionization cross sections are derived in the Born approximation in terms of the momentum transfer without allowance for magnetic interactions. Using these formulas implemented in the LOSS-R code, the ionization cross sections are calculated for the K shells of neutral atoms colliding with protons and also for 1s and 2p electrons of multiply charged heavy ions (nuclear charge Z = 80−90) colliding with bare nuclei and neutral atoms. The calculation results are compared with experimental data and calculations of other authors.  相似文献   

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