共查询到19条相似文献,搜索用时 140 毫秒
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实验用光学多道分析系统(OMA)测量了He2+和Ne,Ar碰撞过程中的发射光谱,结果表明,这些碰撞体系存在着三种激发过程:双电子俘获激发过程、单电子俘获激发过程和直接激发过程。给出了HeI,HeII,NeI,NeII和ArI,ArII谱线的发射截面,并对He2++Ne和He2++Ar两个碰撞体系的发射截面作了一些比较,发现在入射离子速度相同的情况下,后者的发射截面要比前者大得多,并对此进行了定性讨论。OMA的光谱波长范围为200—800nm。入射离子He2+的能量范围为140—340keV。
关键词: 相似文献
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在中能区测量了Cq+(q=1-4)与He,Ne,Ar气体原子碰撞的电子损失截面,计算分析了入射离子损失两个电子与一个电子的总截面比 R21. 单反应道分析无法完全解释所有实验结果,必须同时考虑入射离子的电子损失、电子俘获和靶原子电离各种出射道间的耦合作用. 对于不同靶原子的碰撞,入射离子损失一个电子和两个电子的速度阈值可以由屏蔽和反屏蔽理论解释. 然而,该理论不能完全解释截面比 R21
关键词:
离子-原子碰撞
截面
电子损失 相似文献
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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
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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
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利用冷靶反冲离子动量谱仪,对低能He2+-He碰撞反应中产生的反冲靶离子和炮弹离子进行了符合测量,根据反冲靶离子的动量,研究了转移电离过程中的电荷转移机理.实验结果表明:在20—40 keV能量范围内,靶原子上的一个电子俘获到炮弹离子的基态,另一个电子直接发射到靶的连续态的直接电离及另一个电子俘获到炮弹离子的连续态的过程(ECC)是最主要的转移电离机理,且ECC过程主要发生在大碰撞参数条件下;炮弹离子俘获两个电子处在双激发态的自电离过程的贡献很小.
关键词:
冷靶反冲离子动量谱仪
转移电离机理
离子原子碰撞 相似文献
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We have measured the absolute values of the total cross section of the one-electron capture by He2+ ions in the kinetic energy range 2–30 keV at the Ar atoms. The absolute values of the differential scattering cross sections of He+ ions formed during the one-electron capture and the electron capture with ionization at energies of 2.2, 5.4, and 30 keV have been determined. The electronic states of the formed ions have been determined using collision spectroscopy based on analysis of the change in the kinetic energy of He+ after the interaction. We have measured doubly differential (with respect to the kinetic energy and the scattering angle) cross sections of the formation of free electrons. The free electron formation channels (direct ionization and electron capture with ionization) have been analyzed by calculating the electron terms of the (HeAr)2+ system. The calculated cross section of capture with ionization is in conformity with the cross section measured using collision spectroscopy. 相似文献
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E. Träbert H.-P. Garnir P.-D. Dumont T. Bastin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):25-31
Peculiar properties of ion-atom collision systems, in particular deviations from statistical populations of singlet and triplet
levels, can be studied by optical spectroscopy. We have extended earlier studies by VUV spectroscopy of a number of collision
systems at various collision energies in the 0.01-MeV/nucleon to 1-MeV/nucleon range, involving H2
+, H+, He+, He2+, Ne+, Ar+, and N2
+ as projectiles and Ne, Ar, and N2 as target gases. Statistically significant deviations of the relative intensities of singlet and triplet lines from simple
ratios are observed in the displaced terms of the valence shell of Ne III, corroborating and extending earlier work. For Ar
III, the energy dependences of singlet-to-triplet excitation ratios are very different for different projectiles. For N II,
in contrast, all observed line ratios are practically independent of the projectile energy.
Received 17 November 2000 and Received in final form 31 January 2001 相似文献
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We studied low-energy (~ 1.55 keV) electron-spin-polarized 4He+ ion scattering on a Bi(111) ultrathin film epitaxially grown on a Si(111) substrate. We observed that the scattered ion intensity differed between the incident He+ ions with up and down spins even though Bi is a non-magnetic element. To analyze the origin of this spin-dependent ion scattering (the spin asymmetry), we investigated the detailed relationship between the spin asymmetry and the incident angle, the azimuthal angle, the scattering angle, and the incident energy. All the data indicate that the spin asymmetry originates from the scattering cross section owing to the non-central force in the He+–Bi atom binary collision. The non-central force is most likely attributed to the spin–orbit coupling that acts transiently on the He+ 1s electron spin in the binary collision. 相似文献
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N. Kishimoto M. Matsumoto E. Matsumura K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):75-84
Stereodynamics in ionization of toluene and o-, p-chlorotoluenes by collision
with He*(23S) metastable atoms were investigated by two-dimensional
collision-energy/electron-energy-resolved Penning ionization electron
spectroscopy. Anisotropic interactions around the molecule were studied by
the collision energy dependence of partial ionization cross-sections
(CEDPICS) as well as model potential calculations, and shielding effect by
the methyl group was observed in CEDPICS for ionization from Cl lone-pair
orbitals of o-
chlorotoluene. Attractive interaction with He*(23S)
around the π orbital region was found to be larger for toluene rather
than o-, p-
chlorotoluenes. Exterior electron density (EED) calculation of
partial ionization cross-sections in Penning ionization and negative CEDPICS
for ionization band observed in ca. 4 eV in electron energy indicated that
π-2π+1 shake-up state was observed in
Penning ionization electron spectroscopy of toluene. 相似文献
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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
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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
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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
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Average Energy Loss Measured in Single and Double Electron Capture Collisions of He^2+ on Ar at Low Velocities * 下载免费PDF全文
Employing the recoil ion momentum spectroscopy we investigate the collision between He^2+ and argon atoms. By measuring the recoil longitudinal momentum the energy losses of projectile are deduced for capture reaction channels. It is found that in most cases for single- and double-electron capture, the inner electron in the target atom is removed, the recoil ion is in singly or multiply excited states (hollow ion is formed), which indicates that electron correlation plays an important role in the process. The captured electrons prefer the ground states of the projectile. It is experimentally demonstrated that the average energy losses are directly related to charge transfer and electronic configuration 相似文献