首页 | 本学科首页   官方微博 | 高级检索  
    检索          
共有20条相似文献,以下是第1-20项 搜索用时 124 毫秒

1.  Multiple ionization of argon accompanied by electron loss and capture of 0.22-6.35 MeV C^q+ ions  
   陈林  陈熙萌  邵剑雄  鲁彦霞  丁宝卫  崔莹  高志民  刘玉文  杜娟  谢江山  孙光智  刘兆远《中国物理》,2007年第16卷第8期
   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.    

2.  Investigation of the transfer ionization process in collisions of partially stripped ions on He  
   刘会平  陈熙萌  欧阳晓平  席发元  苏光辉《中国物理 B》,2010年第19卷第6期
   In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22-6.30 MeV C q+ ions and 0.25-6.35 MeV O q+ ions (q=1,2,3,4) with the He atom separately.The cross section ratio f of transfer ionization to single electron transfer is measured,and the dependence of f on both charge state q and energy E of the projectiles is investigated.The electron-structure and the mechanisms leading to transfer ionization affect the dependence of f on q and E.Our measurements,along with other data published previously,suggest a similar dependence of f on charge state and energy of projectile for partially stripped ions over a large energy range.The maximum value of f is approximately 0.17q 0.60 ;the energy corresponding to maximum f is about 160q 0.60 keV/u.    

3.  Production of recoil ions He^i+ accompanied by single electron loss of 0.2-7 MeV C^q+ and 0.25-5 MeV O^q+ (q = 1- 4) ions  
   陈熙萌  鲁彦霞  丁宝卫  刘玉文  崔莹  高志民  付宏斌  杜娟  邵剑雄《中国物理》,2007年第16卷第8期
   Target ionization accompanied with projectile electron loss is investigated for 0.2-7 MeV C^q+ (q = 1 - 4) with He and 0.25-5 MeV O^q+ (q = 1 - 4) with He collisions. For projectile single-electron loss channel, the He double-to-single ionization ratio R is nearly independent of projectile charge state but dependent on the nuclear charge of projectile Zp. The results are analysed with atomic structure qualitatively. So far there have not existed the experimental data comparable with our results, to our knowledge. The ratio R is interpreted in terms of the two-step mechanism. This analysis agrees well with similar experiments in the literature.    

4.  MULTIPLE IONIZATION PROCESS STUDIED WITH COINCIDENCE TECHNIQUE BETWEEN SLOW RECOIL ION AND PROJECTILE ION IN 42 MeV Ar^q+—Ar COLLISIONS  
   T.Tonuma T.Matsuo 等《原子与分子物理学报》,1990年第7卷第4期
   Slow Ar recoil ion Production cross sections by 42 MeV Ar^1 (q=4-14) projectiles were measured using a projectile ion-recoilion coincidence technique in order to provide information on mechanisms of multiple ionization of target atome through pure ionization as well as of that accompaied simultaneously with multiple electron loss or capture of projectiles.The present results suggest that inner-shell electron processes caused through electron transfer into projectiles and also electron ionization by projectiles play a key role in the production of multiply charged recoil ions.    

5.  Cross sections of Oq+(q=1-4) electron loss in collisions with He,Ne and Ar  
   鲁彦霞  路兴强  宋想  张泊丽《中国物理 B》,2011年第20卷第3期
   Electron-loss cross sections of O q+(q = 1 4) colliding with He,Ne and Ar atoms are measured in the intermediate velocity regime.The ratios of the cross sections of two-electron loss to that of one-electron loss R 21 are presented.It is shown that single-channel analysis is not sufficient to explain the results,but that projectile electron loss,electron capture by the projectile and target ionization must be considered together to interpret the experimental data.The screening and antiscreening effects can account for the threshold velocity results,but cannot explain the dependence of the ratio R 21 on velocity quantitatively.In general,the effective charge of the target atom increases with velocity increasing because the high-speed projectile ion can penetrate into the inner electronic shell of target atom.Ne and Ar atoms have similar effective charges in this velocity regime,but He atoms have smaller ones at the same velocities due to its smaller nuclear charge.    

6.  MULTIPLE IONIZATION PROCESS STUDIED WITH COINCIDENCE TECHNIQUE BETWEEN SLOW RECOIL IOH AND PROJECTILE ION IN 42 MeV Ar~(q )-Ar COLLISIONS  
   T.Tonuma  H.Kumagai  T.Matsuo  H.Tawara《原子与分子物理学报》,1990年第4期
   Slow Ar recoil ion production cross sections by 42MeV Ar~(q )(q=4-14)projectiles were measured using a projectile ion-recoilion coincidence technique in order to provide information onmechanisms of multiple ionization of target atoms through pureionization as well as of that accompanied simultaneously with mul-tiple electron loss or capture of projectiles. The present resultssuggest that inner-shell electron processes caused through electrontransfer into projectiles and also electron ionization by projectilesplay a key role in the production of multiply charged recoil ions.    

7.  Electron Capture Process in Collisions of Proton with Excited State of Helium  
   王学容  刘玲  王建国《中国物理快报》,2010年第27卷第12期
   Total and star,selective cross sections for single electron capture (SEC) from the n = 2 excited state of helium colliding by protons are calculated in the energy range of 1.0-100.0 ke V/u by using the two-center atomic orbital close-coupling method. The interaction of the active electron with helium ion is represented by a model potential. Total SEC cross sections show a monotonic decreasing trend with increasing collision energy, and display a different behavior compared with the case from the ground state of helium. It is also found that the dominant reaction channel is captured to the H(2p) state up to 40 keV//u, and then the capture to the H(1s) or H(2s) state becomes more pronounced. Moreover, the alignment dependence on the initial states is obtained for the electron capture from He(2p0) and He (2p1).    

8.  Projectile electron loss in collisions of light charged ions with helium  
   尹永智  王赟  陈熙萌《中国物理 B》,2014年第5期
   We investigate the single-electron loss processes of light charged ions (Li^1+,2+, C^2+,3+,5+, and O^2+,3+) in collisions with helium. To better understand the experimental results, we propose a theoretical model to calculate the cross section of projectile electron loss. In this model, an ionization radius of the incident ion was defined under the classical over-barrier model, and we developed "strings" to explain the processes of projectile electron loss, which is similar with the molecular over-barrier model. Theoretical calculations are in good agreement with the experimental results for the cross section of single-electron loss and the ratio of double-to-single ionization of helium associated with one-electron loss.    

9.  Investigation of transfer ionization in collisions of partially stripped carbon ions with helium at low to intermediate velocities  
   陈熙萌  高志民  刘兆远  丁宝卫  鲁彦霞  付宏斌  邵剑雄  崔莹  张红强  刘玉文  杜娟  孙光智《中国物理》,2007年第16卷第7期
   The ratios of transfer ionization (TI) to single-electron capture (SC) cross sections have been measured for the collisions of partially stripped C^q+ ions (q = 1-4) with He. The collision velocity ranges from 0.7 to 4.4 vo (vo 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 3.7 vo. 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.    

10.  Transfer Ionization Cross-sections in Ar Ions on Neon Collisions  
   MaXinwen LiuHelping ChenXimeng YangZhihu ShenZhiyong WangYoude YuDeyang CaiXiaohong LiuZhaoyuan《近代物理研究所和兰州重离子加速器实验室年报》,2003年第1期
   We measured the charge exchange cross-sections in collisions of Ar^q (q=8, 9, 11, 12) on Ne atoms at low impact energies from 80 keV to 240 keV, and obtained a set of cross-section data. In order to understand the charge exchange processes, we combined the Molecular Classical over-Barrier Model (MCBM) developed by Niehaus[1] with auto-ionization and electron evaporation of multiply excited states. This was described in detail in Refs.[2, 3]. The de-excitation was considered only via Auger process (auto-ionization) in Refs.[4]. In our treatment, the multiply excited states of the projectile undergo Auger decay while the electrons in the multiply excited states of target ions undergo statistical evaporation[5‘6]. For projectile auto-ionization, some criterions based on the Auger electron spectra are applied in order to proceed the sequential decay. To calculate the evaporation probability, one has to get the excitation energy of the system. In our case, the excitation energy was obtained according to the states occupied by the captured electrons based on the MCBM. The values are different from the ones in, but more realistic. If one traces each molecularized electrons to its final states in the processes, one can reproduce each possible reaction channel. The processes discussed can be summarized in the following equation    

11.  SINGLE ELECTRON CAPTURE INTO EXCITED STATES IN COLLISION BETWEEN O~(5+) AND He  
   杨锋  潘广炎  李大万  张文  刘占稳  徐谦  刘惠萍  赵孟春《中国科学B辑(英文版)》,1992年第10期
   The emission spectra of OV singlet lines, OV triplet lines and Hell doublet lines havebeen measured and their emission cross-sections calculated. Only single-electron capture intoexcited states has been observed in the energy range 60--80 keV of the incident O~(5+) ions.Our experimental results on excitation levels are in agreement with those predicted by thediabatic potential diagram for O~(5+) + He collision system.    

12.  Two Electron Transfer and Stabilization in Slow O^6+ and Rare-Gas Collisions  
   薛迎利  于得洋  卢荣春  邵曹杰  阮芳芳  杨治虎  蔡晓红《中国物理快报》,2010年第27卷第7期
   The stabilization ratios R for double-electron transfer, i.e., the cross section ratios of true double capture to total double-electron transfer, are measured in O^6+ +He, Ne and Ar collisions at 6 keV/u. A high R value about 68% is obtained for the He target, while for the Ar target, the R value is only 8%. The high R value for the He target is due to the significant direct population of the (2l, nl′ ) configurations with high n. For the Ar target, the (quasi)symmetric configurations (3l, nl′) lead to the much lower R value. Neglecting the core effects, the O^6+ ion can be taken as a bare ion C^6+ except the occupied ls shell, and then the measured R values are compared with previous experimental results of C^6+ projectile ions at Ne and Ar target, while the occupied ls shell for the C^6+ +He collisions. similar impact velocity. It yields good agreement with the O^6+ +He system results in a higher R value than that in    

13.  Variation of Ionization Mechanisms with q in the Collision of He^2+ with C^q+  
   宁烨 何斌 刘春雷 颜君 王建国《中国物理快报》,2006年第23卷第5期
   The ionization process in the collisions of He^2+ with C^q+ (q = 0-5) is investigated by using the continuum-distorted-wave eikonal-initial-state approximation. Double-differential cross sections for 1s and 2s sub-shells are obtained at the electron-ejected angle θ = 0° with the projectile energy ranging from 30keV/u to 10MeV/u. Variation of ionization mechanisms with q in C^q+ is studied, and the dependences on the projectile energies and target sub-shells are also discussed. It is found that in the whole energy range, the absolute values of soft collision (SC) and binary encounter (BE) peaks decrease with increasing q. For the lower incident energies, the electron capture to the projectile continuum (ECC) peak decrease with increasing q as well as SC and BE peaks. For the higher incident energies (〉 1 MeV/u), the absolute value of ECC peak increases with increasing q, so that the crossings of cross sections appear for C^q+ with different q. This can be explained by the matching of velocities between the projectile and the electron initially bound to the target.    

14.  MULTIPLY CHARGED IONS COLLISIONS WITH ATOMS INTO EXCITED STATES  
   PanGuangyan《原子与分子物理学报》,1990年第7卷第4期
   The emission spectra in collisions between Ions and Atoms have been measured by an Optical Multichannel Analysis System (OMA).The experimental results demonstrate that there are two channels of excitation in collision between single charged ions and atoms and three channels of excitation in collision between double charged ions and atoms.Emission cross cestions and excitation cross sections have been obtained.K.Kadota et al and R.Shingal et al suggested that,under the appropriate conditions,the H4^2 -Li and He^2 Na collision systems can be used efficiently to produce a laser of Lyman-α(30,4nm) and Lyman-β(25.6nm)lines via cascade to He^ (2P)state.    

15.  Ionization and single electron capture in collision of highly charged Ar16+ ions with helium  
   王菲  芶秉聪《中国物理 B》,2008年第17卷第4期
   This paper uses the two-centre atomic orbital close-coupling method to study the ionization and the single electron capture in collision of highly charged Ar^16+ ions with He atoms in the velocity range of 1.2-1.9 a.u.. The relative importance of single ionization (SI) to single capture (SC) is explored. The comparison between the calculation and experimental data shows that the SI/SC cross section ratios from this work are in good agreement with experimental data. The total single electron ionization cross sections and the total single electron capture cross sections are also given for this collision. The investigation of the partial electron capture cross section shows a general tendency of capture to larger n and l with increasing velocity from 1.2 to 1.9 a.u..    

16.  Transfer Ionization of Isocharge Sequence Ion and Ar Collisions  
   CaiXiaohong YuDeyang CaoZhurong LuRongchun YangWei ShaoCaojie《近代物理研究所和兰州重离子加速器实验室年报》,2003年第1期
   The study of multi-electron process has been a very active area of atomic physics research. The simultaneous electron emission and electron transfer is one of the most interesting two-electron processes in the study Of ionatom collisions, In last decade much experimental and theoretical attention has been devoted to the process, named transfer ionization (TI). This process is normally considered as the successive process of the single electron capture and the ionization of the second or more target electrons. The studies of transfer ionization are motivated by the understanding of the role of the electron correlation in ion-atom collisions which is of great interest in basic atomic physics and may provide important information for the applications both in astrophysics and fusion plasmas researches. Different authors have investigated the transfer ionization process by measuring the angular distribution of the emitted electrons. Up to now, the systematic study of the transfer ionization and the dependences of these processes on the collision parameters for the low energy ion-atom collisions are still rarely reported in the literatures.    

17.  Coupled—Channel Investigation of the Collision of Protons and Antiprotons with hydrogen—Like Atoms in the 2s States  
   RedaS.Tantawi《中国物理快报》,2003年第20卷第3期
   The influence of the electric charge of both the projectile and the target nucleus on the cross section of the inelastic collision of protons and antiprotons with atoms is investigated at energies ranging from 1 to 2500Kev,The impact parameter method is used to analyse the cross sections of the excitation of the n=3 states of H atom and He^ ,Li^2 ions being initially in the excited 2s states.The calculated cross sections for hydrogen atome are compared with the other theoretical results based on coupled-channels methods.    

18.  Transfer ionization of the isocharge sequence ion and Ar collisions  
   蔡晓红  于得洋  曹柱荣  卢荣春  杨威  邵曹杰  陈熙萌《中国物理》,2004年第13卷第10期
   The ratios of transfer ionization to single capture for isocharge C^{q+}, N^{q+}, O^{q+}, Ne^{q+} ions on Ar atoms are measured by using position-sensitive and time-of-flight techniques. It is found that the ratio R_{1} increases with nuclear charge Z in a q=4 sequence, and the ratio R_{1} sequences have the minimum values at Z=7 and Z=8 in q=5 and q=6 sequences, respectively, and the ratio R_{1} decreases with the increase in the nuclear charge Z in a q=7 sequence. The results may be explained within the frame of the statistical model. It may be concluded that the transfer ionization depends remarkably upon the electronic structure of the projectile. The projectiles used in this study have the same charge state and velocity, but different electronic structures. The dependence of the ratio R_{1} on q is studied for Ne^{q+}-Ar collisions. The ratio R_{1} is found to increase as q increases for Ne^{q+}-Ar collisions. The measured dependence of the ratio R_{1} on q is compared with the calculation using the molecular Coulomb over-barrier model.    

19.  Ab Initio Calculations of Differential Cross Sections for Single Charge Transfer in ^3He^2+ + ^4He Collisions  
   吴勇 闫冰 刘玲 王建国《中国物理快报》,2007年第24卷第7期
   The single charge transfer process in ^3He^2+ + ^4He collisions is investigated using the quantum-mechanical molecular- orbital close-coupling method, in which the adiabatic potentials and radial couplings are calculated by using the ab initio multireference single- and double-excitation configuration interaction methods. The differential cross sections for the single charge transfer are presented at the laboratorial energies E = 6 keV and lOkeV for the projectile ^3He^2+. Comparison with the existing data shows that the present results are better in agreement with the experimental measurements than other calculations in the dominant small angle scattering, which is attributed to the accurate calculations of the adiabatic potentials and the radial couplings.    

20.  The direct ionization processes in the collisions of partially stripped carbon and oxygen ions with helium atoms at low-to-intermediate energies  
   周春林  邵剑雄  陈熙萌  孙光智  邹贤容《中国物理 B》,2008年第17卷第11期
   The values of direct double- to-single ionization ratio R of helium atoms induced by C^q+, O^q+ (q = 1 -4) ions at incident energies from 0.2 to 8.5MeV are measured. Based on the existing model (Shao J X, Chen X M and Ding B W 2007 Phys. Rev. A 75 012701) the effective charge of the projectile is introduced to theoretically estimate the value of R for the partially stripped ions impacting on helium atoms. The results calculated from our "effective charge" model are in good agreement with the experimental data, and the dependence of the effective charge on the ionization energy of the projectile is also discussed qualitatively.    

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号