共查询到19条相似文献,搜索用时 187 毫秒
1.
采用冷靶反冲离子动量谱仪技术,实验测量了能量为6和8.6 keV/u N6+-Ne碰撞的单电子俘获过程,得到了主量子数n分辨的态选择截面和炮弹离子的散射角分布。实验结果表明,单电子主要被俘获到n=3和n=4的态。这与分子库仑过垒模型计算的反应窗所预测的结果符合。同时,实验获得了单电子俘获到n=3和n=4量子态的角微分截面,此结果与经典模型的计算结果存在较大差别,主要原因是碰撞反应过程的多通道耦合效应。 相似文献
2.
在Ne~+和He碰撞过程的研究中,测量了NeⅠ、NeⅡ以及HeⅠ主量子数3~4的单态和三重态的发射截面。实验证明:此碰撞体系存在着两种激发过程,一种是电子俘获激发过程,另一种是直接激发过程,即电子组态重新排列激发过程。入射离子Ne~+的实验室能量范围为70~150KeV° 相似文献
3.
利用“二态矢量模型”详细研究了高电荷态O7+,N6+离子入射Al表面时中间里德伯态的形成过程,给出了电子被俘获至不同量子数(n A=2-7)的几率,以及电子俘获至里德伯态最可能的离子-表面距离.计算结果表明,较大的主量子数nA对应较小的里德伯态几率,因此O7+,N6+离子入射Al表面时辐射的X射线主要来源于较小的n A至基态的退激.为了验证计算结果,测量了O7+,N6+离子入射Al表面的X射线发射谱,并运用FAC程序计算了不同高里德伯态退激到基态的跃迁能(np–1s).实验测量到O,N的K-X射线峰,其特征峰的中心值接近主量子数n=2至n=1的跃迁能,说明发射的X射线主要来源于2p–1s的跃迁,与“二态矢量模型”理论计算的几率一致. 相似文献
4.
利用冷靶反冲离子动量谱仪装置系统研究了20-40 keV He2+-He碰撞体系的态选择单电子俘获过程,实验获得了单电子俘获过程的态选择截面以及角微分截面.在所研究的能区范围,电子俘获到L壳层的截面最大,为主要的反应道,这与分子库仑过垒模型的反应窗理论的预测一致.实验测量的态选择截面与原子轨道紧耦合的计算结果很好地符合,与光谱方法的测量结果存在一定的差别,主要原因是光谱方法不能测量完整的反应通道信息.实验结果表明,总角微分截面在小角度范围主要来源于电子俘获到基态的贡献,在大角度范围主要来自电子俘获到激发态的贡献;电子俘获到基态的和激发态的角微分截面均出现振荡结构,这种振荡来源于电子俘获反应中分子轨道之间的相干效应.实验测量的角微分截面与其他实验和紧耦合方法的计算结果进行了比较和分析. 相似文献
5.
6.
经典轨迹蒙特卡罗(CTMC)方法是研究离子-原子碰撞系统电荷交换过程的常用方法,广泛应用于天体物理以及实验室等离子体环境下重粒子碰撞过程的研究.本文利用四体碰撞模型(4-CTMC)研究了包括两个束缚电子的四体碰撞过程,通过数值求解四体碰撞系统的哈密顿运动方程,计算了高电荷态入射离子(Li3+,Be4+和O7+)同氦原子在大能量范围的单、双电子电离和俘获截面.H++He碰撞截面的计算中,在50—200 keV/amu的入射能区,4-CTMC的结果几乎重复了实验结果.在高电荷态入射情形下,4-CTMC计算的单电子电离和俘获截面值相较于三体碰撞模型(3-CTMC)在100—500 keV/amu的入射能区内与实验符合更好.尽管4-CTMC和3-CTMC忽略了电子关联,均高估了双电子电离和俘获截面(与实验值相比),但4-CTMC的结果更接近实验. 相似文献
7.
8.
9.
双电荷离子Ar~(2 )和He、Ne原子碰撞中,存在着三种碰撞激发过程,一是双电子俘获激发过程,二是单电子俘获激发过程,三是直接激发过程。实验用光学多道分析系统(OMA)对这些过程进行了光学测量,得到了ArⅠ、ArⅡ、NeⅠ、NeⅡ、HeⅠ、HeⅡ谱线的发射截面,并对这些发射截面进行了比较,发现在入射离子速度相同的情况下,Ar~(2 ) Ne碰撞体系的发射截面要比Ar(2 ) He碰撞体系的大。OMA的光谱波长范围是200—800um。入射离子Ar(2 )的能量范围是140—340keV。 相似文献
10.
11.
应用双中心原子轨道强耦合方法研究He2+-H-碰撞的单次电荷转移过程.计算中,对入射粒子He2+,包含n=1~7的所有束缚态,计算的能量本征值与NIST标准数据在百分之几的精度内符合很好;对靶H-,包括一个束缚态1s和五个连续态ns(n=2~6),束缚态能量与他人理论结果一致.在4~400 keV的入射粒子能量范围,计算单电子俘获过程的总截面及到各个壳层上的态选择截面.发现在较低的入射粒子能量,电子主要俘获到He+离子主量子数n=3~5的壳层,高能区俘获到n=2的壳层为主;对同一主量子数n,在低能区俘获到高角动量态(l=n-1,n-2)的电荷转移截面相对较大,在高能区主要俘获到l=1的p壳层.同时还计算入射粒子能量分别为4 keV和400 keV时,电子俘获到激发态辐射退激发产生的电荷转移发射光谱,并发现cascade效应的影响很大. 相似文献
12.
利用冷靶反冲离子动量谱仪装置系统研究了20—40 keV He2+-He碰撞体系的态选择单电子俘获过程,实验获得了单电子俘获过程的态选择截面以及角微分截面.在所研究的能区范围,电子俘获到L壳层的截面最大,为主要的反应道,这与分子库仑过垒模型的反应窗理论的预测一致.实验测量的态选择截面与原子轨道紧耦合的计算结果很好地符合,与光谱方法的测量结果存在一定的差别,主要原因是光谱方法不能测量完整的反应通道信息.实验结果表明,总角微分截面在小角度范围主要来源于电子俘获到基态的贡献,在大角度范围主要来自电子俘获到激发态的贡献;电子俘获到基态的和激发态的角微分截面均出现振荡结构,这种振荡来源于电子俘获反应中分子轨道之间的相干效应.实验测量的角微分截面与其他实验和紧耦合方法的计算结果进行了比较和分析.
关键词:
冷靶反冲离子动量谱仪
态选择电子俘获
态选择截面
角微分截面 相似文献
13.
K. Kadota D. Dijkkamp R. Van Der Woude Pan Guang Yan F.J. De Heer 《Physics letters. A》1982,88(3):135-139
We have studied the He2+-Li collision system at laboratory energies between 15 and 150 keV using optical methods. From the measured emission cross sections we derive state-selective capture cross sections for n = 2,3,4 and n ? 5 states of the He+ ions. Our data are consistent with theoretical predictions of Bransden and Ermolaev. The total capture cross sections as evaluated from our emission cross section data, agree very well with the results of McCullough et al. obtained from projectile charge detection measurements. Near 15 keV our emission cross sections for 30.4 nm and 25.6 nm are much larger than those measured previously by Barrett and Leventhal at slightly lower energies. 相似文献
14.
介绍了对于Na+ 离子和Rb(5s ,5p)原子碰撞中态选择单电子俘获微分截面的理论计算,并与实验数据进行比较,实验结果是离子与在磁光学阱中用激光冷却的碱金属靶原子碰撞而测量到的;还对高能量质子引起的He原子的转移电离进行了理论研究,在Shakeoff模型的基础上 ,分析解释了转移电离截面与单电子俘获截面的比值 ,并与最新实验结果作了比较. We report a theoretical study of state-selective differential single-electron capture cross sections between Na + and Rb(5s, 5p) atoms. The experimental data have been obtained with laser cooled target in a magnetic optical trap. We also report a theoretical study of transfer ionization of He by protons at high collision energies and analyze the transfer ionization cross section with respect to single electron capture cross section in terms of a shakeoff model. 相似文献
15.
The quantum dynamics of charge exchange (electron capture) and excitation processes in proton collisions with Sn atoms is studied for the first time by using the two-centre atomic orbital close coupling method. The expansion basis includes the lowest nine states of singlet and triplet symmetry of Sn and all the states with n ≤ 8 of the H atom. The spin-resolved state-selective charge exchange (up to n = 5) and excitation cross sections are calculated in the energy range of 0.5 − 100 keV . Strong coupling between the electron capture and excitation channels is observed in the low-energy (E ≤ 10 keV) region associated with the energy quasi-resonance of some projectile and target states. The intensities of some strong Sn spectral lines are also calculated for a number of typical tokamak edge plasma temperatures. 相似文献
16.
Sequential over-barrier ionization of multi-electron atoms in the tens-to-hundreds keV/u energy range 下载免费PDF全文
Our previous work on the classical over-barrier ionization model for helium double ionization is extended to the complex multi-electron system of Ne.The total and q-fold ionization cross sections are calculated at energies ranging from a few tens to several hundred keV/u.The calculation results are in good agreement with the experimental data,and the energy dependence of the cross sections suggests that the multi-ionization of a strong perturbated complex atom is probably the sequential over-barrier ionization process. 相似文献
17.
C. Bauer H. Richter P. Gippner R. Mann W. Rudolph B. Eckhardt K. O. Groeneveld 《Zeitschrift für Physik A Hadrons and Nuclei》1981,303(1):13-22
Absolute Ag, Ta and AuL-shell X-ray cross sections were measured using protons,4He,14N as well as20Ne ions in the energy range of 0.125–4 MeV/amu. By means of single-hole fluorescence yields experimental ionization cross sections were deduced and compared with calculations according to the corrected PWBA model — PWBA(BPCR). With decreasing asymmetry of the collision system the experimental cross sections exceed the predictions of the direct ionization theory. This is caused by an increasing contribution of a competing KL charge exchange mechanism which was investigated in detail for Ne+Ag. The Lapicki and Losonsky capture model was found to fail at energiesE<1 MeV/amu because adiabatic relaxation effects in the projectileK-shell become important. An estimation by means of the Nikitin model led to more physically comprehensible results at the lowest ion velocities investigated. 相似文献
18.
Influence of core property on multi-electron process in slow collisions of isocharged sequence ions with neon 下载免费PDF全文
Influence of core property on multi-electron process in the collisions of q=6-9 and 11 isocharged sequence ions with Ne is investigated in the keV/u region.The cross-section ratios of double-,triple-,quadruple-and total multi-electron processes to the single electron capture process as well as the partial ratios of different reaction channels to the relevant multi-electron process are measured by using position-sensitive and time-of-flight techniques.The experimental data are compared with the theoretical predictions including the extended classical over-barrier model,the molecular Columbic barrier model and the semi-empirical scaling law.Results show a core effect on multi-electron process of isocharge ions colliding with Neon,which is consistent with the results of Helium we obtained previously. 相似文献
19.
Our measurements of Ne K and N K X-ray cross sections for N3+,4+,5+,6+,7+, ions incident on a thin Ne target at energies from 9 to 54 MeV indicate that charge exchange plays a minor role compared to ionization in producing Ne K vacancies over that energy range. 相似文献