共查询到17条相似文献,搜索用时 703 毫秒
1.
采用反冲离子飞行时间-散射离子位置灵敏符合测量技术,测量了能量范围在0.7v0—4.4v0(v0为玻尔速度)的碳离子Cq+(q=1—4)与He原子碰撞过程不同出射道靶原子的双电离与单电离截面比R,包括入射离子不损失电子(直接电离)的出射道(Rq,q),入射离子俘获一个电子的出射道(Rq,q-1)和入射离子损失一个电子的出射道(Rq,q+1),并研究了R随入射C离子的能量及电荷态的变化关系.实验表明,对给定电荷态的入射离子,靶原子的双电离与单电离截面比R与出射道有很强的依赖关系,即Rq,q<Rq,q+1<Rq,q-1.直接电离出射道截面比Rq,q与入射离子电荷态几乎无关,而入射离子俘获一个电子的出射道和损失一个电子的出射道靶原子双电离与单电离截面比Rq,q-1和Rq,q+1却与入射离子电荷态有很强的关系.采用原子极化理论和电子屏蔽与反屏蔽作用对实验结果进行了解释.
关键词:
离子-原子碰撞
电离
截面比 相似文献
2.
3.
采用位置灵敏探测和飞行时间技术测量了等电荷态离子Cq+、Nq+、Oq+、Neq+(q=4,5,6,7)与He原子碰撞中,转移电离截面与单电子俘获截面的比值R.研究了相同q入射的情况下,R与入射离子核电荷数Z的依赖关系,在统计蒸发模型的基础上对实验结果进行了解释. 相似文献
4.
采用位置灵敏探测和飞行时间技术测量了等电荷态离子C^q 、N^q 、O^q 、Ne^q (q=4,5,6,7)与He原子碰撞中,转移电离截面与单电子俘获截面的比值Ro研究了相同q入射的情况下,R与入射离子核电荷数Z的依赖关系。在统计蒸发模型的基础上对实验结果进行了解释。 相似文献
5.
多电子激发态离子的自由离衰变处理方法 总被引:2,自引:1,他引:1
马新文 《原子与分子物理学报》1999,16(2):203-210
在分析当前描述离子与原子碰撞的经典理论模型的基础上,详细讨论了处理多电子激发态自电离衰变问题的一些新的思路,把高电荷态离子与原子碰撞反应中的电子转移过程分为四阶段描述,并依据能量守恒原理,规范了处理多电子激发态离子发生自电离衰变的规则,自洽地解决碰撞中间过程中俘获多电子后的离子发生自电离向末态衰变的问题,并分析和比较了新的计算结果与实验结果。 相似文献
6.
多电子激发态离子的自电离衰变处理方法 总被引:5,自引:3,他引:2
马新文 《原子与分子物理学报》1999,(2)
在分析当前描述离子与原子碰撞的经典理论模型的基础上,详细讨论了处理多电子激发态自电离衰变问题的一些新的思路,把高电荷态离子与原子碰撞反应中的电子转移过程分为四阶段描述,并依据能量守恒原理,规范了处理多电子激发态离子发生自电离衰变的规则,自洽地解决碰撞中间过程中俘获多电子后的离子发生自电离向末态衰变的问题,并分析和比较了新的计算结果与实验结果 相似文献
7.
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
8.
采用位置灵敏探测和飞行时间技术研究了高电荷态Xe离子(q=15,17,19,21,23)与He原子碰撞中双电子转移截面与单俘获截面比随入射离子电荷态的变化规律.提出一步过程假定,对扩展的经典过垒(ECB)模型进行了修正,利用修正模型计算得到的单、双电子转移绝对截面与Andersson等人和Selberg等人的实验结果符合得很好,所得截面比与本实验得到的双电子转移截面与单电子俘获截面符合得比较好. 相似文献
9.
采用位置灵敏探测和飞行时间技术研究了高电荷态Xe离子(q=15,17,19,21,23)与He原子碰撞中双电子转移截面与单电子转移截面比随入射离子电荷态的变化规律.提出一步过程假定,对扩展的经典过垒(ECB)模型进行了修正,利用修正模型计算得到的单、双电子转移绝对截面与Andersson等人和Selberg等人的实验结果很好符合,所得截面比与本实验得到的双电子转移截面与单电子俘获截面比较好符合.
关键词:
离子 原子碰撞
电荷转移
一步过程 相似文献
10.
实验测量了1.7v0-4.2v0(v0为玻尔速度,v0=2.19×108 cm/s)的C3+与He,Ne,Ar原子碰撞过程中单电子转移绝对截面.将实验结果与多体经典轨道蒙特卡罗模拟计算结果做了比较,发现测量结果与多体经典轨道蒙特卡罗模拟计算结果在趋势上相符.当入射离子速度在1.7v0-2.0v0时,因多体经典轨道蒙特卡罗方法计算时不能考虑多电子关联态俘获和极化效应的影响,实验值大于计算值.当入射离子速度在2.2v0-4.2v0时,由于被俘获电子对入射离子的不完全屏蔽,加上电子间的动态关联及有效电荷的影响,实验结果先与多体经典轨道蒙特卡罗计算结果符合很好,而后逐渐大于计算值.此外,还根据转移电离与单电子俘获的截面比简单分析了转移电离机制. 相似文献
11.
MJ Singh DO Kataria N Madhavan P Sugathan JJ Das DK Awasthi AK Sinha R Shanker 《Pramana》1999,53(4):743-764
A projectile ion-recoil ion coincidence technique has been employed to study the multiple ionization and the charge transfer
processes in collisions of 60–120 MeV Si
q+ (q = 4−14) ions with neutral argon atoms. The relative contribution of different ionization channels, namely; direct ionization,
electron capture and electron loss leading to the production of slow moving multiply charged argon recoil ions have been investigated.
The data reported on the present collision system result from a direct measurement in the considered impact energy for the
first time. The total ionization cross-sections for the recoil ions are shown to scale as q
1.7/E
p
0.5
, where E
p is the energy in MeV of the projectile and q its charge state. The recoil fractions for the cases of total- and direct ionizations are found to decrease with increasing
recoil charge state j. The total ionization fractions of the recoils are seen to depend on q and to show the presence of a ‘shell-effect’ of the target. Further, the fractions are found to vary as 1/j
2 upto j = 8+. The average recoil charge state 〈j〉 increases slowly with q and with the number of lost or captured electrons from or into the projectile respectively. The projectile charge changing
cross-sections σ
qq′ are found to decrease with increasing q for loss ionization and to increase with q for direct-and capture ionization processes respectively. The physics behind various scaling rules that are found to follow
our data for different ionization processes is reviewed and discussed. 相似文献
12.
Multiple ionization of argon accompanied by electron loss and capture of 0.22-6.35 MeV C^q+ ions 下载免费PDF全文
In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^+ (q = 1 - 4) ions with argon atoms. The partial cross section ratios of the double, triple, quadruplicate ionization to the single ionization (or the single capture) of argon associated with single electron loss (or single electron capture) by the projectile are measured and compared with the previous experimental results. In the present experiment, it is observed that the ratios of ionization cross sections R associated with single loss and single capture depend strongly on the projectile charge state and vary significantly with different reaction channels as impact energy increases. In addition, this paper gets empirical scaling laws for the ionization cross section ratios R corresponding to the projectile single loss and finds that the ratios of the double ionization to the single ionization associated with single electron capture remain constant in the present energy range. 相似文献
13.
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
14.
实验测量了1.7v0—4.2v0(v0为玻尔速度,v0=2.19×108cm/s)的C3+与He,Ne,Ar原子碰撞过程中单电子转移绝对截面.将实验结果与多体经典轨道蒙特卡罗模拟计算结果做了比较,发现测量结果与多体经典轨道蒙特卡罗模拟计算结果在趋势上相符.当入射离子速度在1.7v0—2
关键词:
离子-原子碰撞
单电子转移
绝对截面 相似文献
15.
B. Coupier B. Farizon M. Farizon M.J. Gaillard F. Gobet N.V. de Castro Faria G. Jalbert S. Ouaskit M. Carré B. Gstir G. Hanel S. Denifl L. Feketeova P. Scheier T.D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):459-468
Ionization and fragmentation of water and uracil molecules was studied both by electron and proton impact. A special coincidence
technique allows on an event by event basis the investigation of product ions formed upon the collision of protons with neutral
molecules including the identification of the charge state of the projectile. This enables the characterization of the ionization
processes occurring, i.e. direct ionization, single electron capture or double electron capture for 0, 1 or 2 electrons that are transferred from the
target to the projectile, respectively. For uracil the fragmentation patterns obtained by electron and proton impact ionization
reveal close similarities and indicate a comparable amount of excitation for the two different ionization mechanisms at high
enough projectile energies.
Received 25 February 2002 Published online 13 September 2002 相似文献
16.
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
17.
Investigation of transfer ionization in collisions of partially stripped carbon ions with helium at low to intermediate velocities 下载免费PDF全文
The ratios of transfer ionization (TI) to single-electron
capture (SC) cross sections have been measured for the
collisions of partially stripped Cq+ ions (q=1--4) with
He. The collision velocity ranges from 0.7 to 4.4v0
(v0 is the Bohr velocity). The projectile-ion and
recoil-ion coincidence technique is used to separate the
processes of TI and SC. The ratios reach the maximum when the
velocity is about 3.7v0 This can be explained
qualitatively based on the two-step mechanism. The experimental
results are also compared with the results calculated using the
classical trajectory Monte Carlo (CTMC) method. The CTMC results
are in agreement with the experimental data basically. The
discrepancies in higher velocity region are interpreted by the
effective charge effect. 相似文献