30 results on '"Ximeng Chen"'
Search Results
2. Neutralization of low energy Na+ ions in grazing scattering on clean and water covered Cu(1 1 0) surfaces
- Author
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Xinyue Guo, Xuan Liu, Zheng Zhang, Yanling Guo, Mingxuan Wei, Ximeng Chen, Guangzhi Sun, Lei Wang, Liyuan Yin, Shunli Qiu, Wei Luo, and Lin Chen
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Nuclear and High Energy Physics ,Materials science ,Scattering ,Analytical chemistry ,Fraction (chemistry) ,02 engineering and technology ,Rate equation ,021001 nanoscience & nanotechnology ,Alkali metal ,01 natural sciences ,Dissociation (chemistry) ,Ion ,0103 physical sciences ,Molecule ,Work function ,010306 general physics ,0210 nano-technology ,Instrumentation - Abstract
keV-energy Na+ ions are scattered from clean and water covered Cu(1 1 0) surfaces in grazing incidence. For both surfaces the pronounced Na° fractions decrease with incident energy. In particular, the lower Na° fraction has been observed for the water covered Cu(1 1 0) surface. The simple calculations using rate equation are presented to compare with the experimental data. The calculation is in agreement with the experimental data. It indicates that the water covered Cu(1 1 0) surface has the slightly higher work function due to water molecules dissociation and forming hydroxyl groups, so that the neutral fraction on water covered Cu(1 1 0) is lower than that on the clean surface.
- Published
- 2021
3. Impurity element analysis of aluminum hydride using PIXE, XPS and elemental analyzer technique
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Lin Chen, Yanling Guo, Yan Zhang, Ximeng Chen, and Zheng Zhang
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Nuclear and High Energy Physics ,Spectrum analyzer ,Ion beam analysis ,Materials science ,Silicon ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Hydrogen storage ,chemistry ,X-ray photoelectron spectroscopy ,Impurity ,0210 nano-technology ,Instrumentation ,Mass fraction ,Carbon - Abstract
Aluminum hydride (AlH3), an attractive hydrogen storage material, plays an important role in rocket and aerospace industry. The impurities in aluminum hydride may seriously cause the deterioration in its properties and stability. Mixing AlH3 sample with the known content of silicon, we distinguish the elements in AlH3 and determine their concentration by using PIXE, XPS and elemental analyzer. Al, Si, Cl, Ca and Fe were identified by PIXE. XPS technique was used to measure the oxidized product of the mixed silicon. C, H content were obtain from the elemental analyzer. The results of the impurity concentration show the effectiveness of the synergy among these techniques except carbon. The XPS result from the pristine sample shows the concentration of carbon is 6 times larger than the major element Al while the result from the elemental analyzer is only 0.620 wt%. It suggests that the XPS technique is surface-sensitive and not well suited to the determination of the bulk concentration of carbon. The mass fraction ratio of Al to H is μ Al / H = 8.718 27 3 , which indicates that the product partly decomposes.
- Published
- 2021
4. Low-energy Na+ neutralization on Al(1 1 1) and Cu(1 1 0) surfaces at grazing incidence
- Author
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Liyuan Yin, Zheng Zhang, Xinyue Guo, Bin Ding, Pinyang Liu, Xuan Liu, Yuanqing Shi, Xu Wang, Mingxuan Wei, Xiaoxun Song, Ximeng Chen, Lei Wang, Yanling Guo, and Lin Chen
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Nuclear and High Energy Physics ,Range (particle radiation) ,Materials science ,Scattering ,Jellium ,Electron ,01 natural sciences ,Molecular physics ,010305 fluids & plasmas ,Ion ,Metal ,visual_art ,Excited state ,0103 physical sciences ,visual_art.visual_art_medium ,010306 general physics ,Instrumentation ,Excitation - Abstract
Jellium model is well known and used to understand the neutralization of alkali-metal ions on metal surfacesbut we find it cannot explain our experiments for the neutralization of 0.4 keV and 0.8 keV Na+ ions on Al(1 1 1) and Cu(1 1 0) surfaces in grazing incidence. As the exit angle increases neutral fractions on Cu(1 1 0) surface decreases first and then increases which is similar to our previous results at large scattering angles. While for the Al(1 1 1) surface we observe opposite characteristics. This anomalous bell-shaped feature cannot be explained by the Jellium model. One possible explanation is the inner 2p electron promotion at smaller exit angles this may cause the Na* excited states to be generated and produce excess Na+ ions while the similar electronic excitation process is inefficient for the Cu(1 1 0) surface in the present energy range.
- Published
- 2020
5. Effects of transmutation elements on hydrogen trapping ability of vacancy in tungsten
- Author
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Fei Ren, Ximeng Chen, Yanling Guo, Lin Chen, and Wen Yin
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Nuclear and High Energy Physics ,Fusion neutron ,Materials science ,Hydrogen ,Nuclear transmutation ,chemistry.chemical_element ,02 engineering and technology ,Trapping ,Tungsten ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,010305 fluids & plasmas ,chemistry ,Vacancy defect ,0103 physical sciences ,Irradiation ,Hydrogen bubble ,0210 nano-technology ,Instrumentation - Abstract
It is well known that vacancy (Vac) can trap multiple hydrogen (H) atoms, and many Vac-rhenium (Re) and Vac-osmium (Os) clusters can be formed in tungsten (W) under fusion neutron irradiation, but the behaviors of H in Vac-Re/Os clusters are still unclear. Therefore, in this work, first-principles calculations are used to investigate the effects of transmutation elements of Re and Os on the H trapping ability of vacancy in W. We find that the presence of multiple Re/Os atoms around vacancy can significantly decrease the trapping energy of vacancy on H and the number of H atoms trapped in vacancy in W, thus Re/Os has an inhibiting effect on the growth of H bubble. Furthermore, Os has more prominent influence than Re for H trapping ability of vacancy in W. In addition, compared with VacHm in pure W, the presence of 8 Re atoms around vacancy in W would increase the stability of VacHm for m ≤ 4, but reduce the stability of VacHm for m > 4. Based on those results, we can qualitatively explain the recent experimental phenomenon.
- Published
- 2019
6. Charge transfer of oxygen negative ions scattering on dissociated H2O-covered Cu(1 1 0) surface
- Author
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Yunqing Xiao, Yanling Guo, Ximeng Chen, Yachao Zhu, Fei Ren, Y.H. Li, Xin Zhang, Pinyang Liu, Yuanqing Shi, Lin Chen, and Lei Gao
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Nuclear and High Energy Physics ,Materials science ,Scattering ,Charge (physics) ,02 engineering and technology ,Rate equation ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,Ion ,Auger ,Ionization ,0103 physical sciences ,Work function ,Specular reflection ,010306 general physics ,0210 nano-technology ,Instrumentation - Abstract
Charge transfer during oxygen negative ion surface scattering is performed to investigate the electronic interaction for the water/Cu system as a function of incident velocity. We find that both positive and negative ion fractions increase with incident velocity for the specular scattering condition. The positive ions produced close to the surface can be understood by the mechanisms of collision-induced ionization and Auger ionization, and they finally survive from the resonant and/or Auger neutralization, which are well described by the exponential scaling. The negative ions are formed through the resonant charge transfer, and the velocity dependence has been explained by the kinematically parallel velocity effect and the surface work function. The modified rate equation taking into account these two factors is in rough agreement with the experimental result.
- Published
- 2019
7. Neutralization of keV-energy alkali-metal ions colliding at gold surfaces
- Author
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Yunqing Xiao, Pinyang Liu, Vladimir A. Esaulov, Yuanqing Shi, Ximeng Chen, Yanling Guo, Lin Chen, Yachao Zhu, and Lei Gao
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Nuclear and High Energy Physics ,Range (particle radiation) ,Materials science ,Scattering ,02 engineering and technology ,Escape velocity ,021001 nanoscience & nanotechnology ,Alkali metal ,01 natural sciences ,Ion ,Azimuth ,0103 physical sciences ,Perpendicular ,Work function ,Atomic physics ,010306 general physics ,0210 nano-technology ,Instrumentation - Abstract
Li+ and Na+ ions are scattered from Au(1 1 0) and Au(1 1 1) surfaces in the keV-energy range, respectively. The pronounced Li° and Na° fractions non-monotonically vary with incident energy and exit angle for high work function gold surfaces. In particular, the azimuthal angle dependence of Li° fraction has been observed at low incident energies for a grazing exit angle. The simple calculations are presented to compare with the experimental data. Our findings clearly indicate that both the perpendicular and parallel exit velocity affect the final neutral fraction.
- Published
- 2019
8. L X-ray production in ionization of 48 Cd and 49 In by 75–250 keV protons
- Author
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Yuyu Wang, Guoqing Xiao, Rui Cheng, Ximeng Chen, Yongtao Zhao, Yu Lei, Xianming Zhou, Xinwen Ma, and Yanhong Chen
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Physics ,Nuclear and High Energy Physics ,Range (particle radiation) ,Astrophysics::High Energy Astrophysical Phenomena ,X-ray ,010403 inorganic & nuclear chemistry ,01 natural sciences ,0104 chemical sciences ,Ionization ,Yield (chemistry) ,0103 physical sciences ,Atomic physics ,010306 general physics ,Instrumentation - Abstract
L-shell X-rays of 48Cd and 49In have been measured for the bombardment of protons in the energy range 75–250 keV in steps of 25 keV. The individual Lι, Lα, Lβ, Lγ and total L X-ray production cross sections were extracted from the yield. The results were compared with theoretical predictions of PWBA, ECPSSR and ECUSAR, as well as with experimental results of other authors. Good agreements were observed for our data with others and ECPSSR or ECUSAR calculations. The influence of using different atomic parameter databases is also discussed.
- Published
- 2018
9. L x-ray production in ionization of 60Nd by 100–250 keV protons
- Author
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Yuyu Wang, Guoqing Xiao, Yu Lei, Rui Cheng, Ximeng Chen, Yanhong Chen, Yongtao Zhao, and Xianming Zhou
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Nuclear and High Energy Physics ,Proton ,Relative intensity ,Chemistry ,Photon radiation ,X-ray ,Electron ,010403 inorganic & nuclear chemistry ,01 natural sciences ,0104 chemical sciences ,Ionization ,0103 physical sciences ,Energy shift ,Atomic physics ,010306 general physics ,Instrumentation - Abstract
L x rays of Nd have been measured for the bombardment of protons with the energies of 100–250 keV. It is found that Lγ 2 (abbreviation of Lγ 2,3,4,4 ′) x-ray emission is largely enhanced by proton impact, compared to the case of photon radiation. It is proposed that is caused by the multiple-ionization of outer-shell electrons. To verify this explanation, the enhancement for relative intensity ratio of Lι and Lβ 2 to Lα x ray and the energy shift of various L-subshell x rays are discussed. In addition, the production cross sections of Lι, Lα, Lβ and Lγ x ray are obtained and compared with theoretical calculations of PWBA, ECPSSR and ECUSAR, along with various atomic parameter databases.
- Published
- 2017
10. Negative ion production in energetic O − and C − ions scattering on HOPG
- Author
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Yanling Guo, Feifei Xiong, Yunqing Xiao, Jianjie Lu, Shunli Qiu, Pinyang Liu, Lin Chen, Lei Gao, Ximeng Chen, and Yuefeng Liu
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Nuclear and High Energy Physics ,Work (thermodynamics) ,Chemistry ,Scattering ,chemistry.chemical_element ,02 engineering and technology ,Escape velocity ,021001 nanoscience & nanotechnology ,01 natural sciences ,Oxygen ,Ion ,Highly oriented pyrolytic graphite ,Physics::Plasma Physics ,0103 physical sciences ,Specular reflection ,Atomic physics ,010306 general physics ,0210 nano-technology ,Instrumentation ,Carbon - Abstract
In this work, we present negative-ion fractions as a function of exit velocity and angle after keV-energy negative oxygen and carbon ions scattering on a highly oriented pyrolytic graphite (HOPG) surface, at a scattering angle of 38°. The negative-ion fractions increase monotonously with the increase of exit velocity for specular scattering, while negative-ion fractions present a bell-shaped dependence on exit angle. In order to gain further insight into the nature of charge transfer on HOPG, a modified charge transfer model involving the contribution of positive ions has been proposed and roughly reproduced the velocity and angle dependences of negative-ion fractions.
- Published
- 2017
11. X-ray and kinetic electron emission by keV proton impacting on fusion-relevant tungsten
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Guoqing Xiao, Rui Cheng, Zhongfeng Xu, Yongtao Zhao, Ximeng Chen, Xianming Zhou, Lixia Zeng, Yu Lei, Yuyu Wang, and Yanhong Chen
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Nuclear and High Energy Physics ,Core charge ,Chemistry ,Electron capture ,Astrophysics::High Energy Astrophysical Phenomena ,Electron energy loss spectroscopy ,Electron multiplier ,01 natural sciences ,010305 fluids & plasmas ,Field electron emission ,Ionization ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Atomic physics ,Proton emission ,010306 general physics ,Valence electron ,Instrumentation - Abstract
We have measured the electron and X-ray emission of tungsten bombarded with proton in the energy range of 50–250 keV. It is found that the total electron yield mainly consists of kinetic electron emission, which results from the excited valence electrons, and presents a similar trend to the curve of stopping power. The ratio between electron yield and electronic energy loss is not constant, but decreases with increasing incident energy. The behavior is interpreted by an expected competitive mechanism of ionization between different shell electrons of target atom. The explanation is verified by the experimental increase of M-shell X-ray emission yield, and the measured and calculated ionization cross section of core and valence electrons.
- Published
- 2017
12. The nanostructure formation on muscovite mica surface induced by intermediate-energy ions
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G. Wang, Xueyang Lv, Q. Zhang, Hq. Zhang, S. Guan, Z.Y. Liu, Jianxiong Shao, Ximeng Chen, Juanjuan Jia, Peng Zhou, Ying Cui, Liang Chen, and Zhou Chunlin
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Quantitative Biology::Biomolecules ,Nuclear and High Energy Physics ,Range (particle radiation) ,Nanostructure ,Materials science ,Muscovite ,Analytical chemistry ,chemistry.chemical_element ,Nanotechnology ,engineering.material ,Ion ,chemistry ,engineering ,Lithium ,Mica ,Nuclear Experiment ,Instrumentation ,Carbon ,Hillock - Abstract
Muscovite mica sheets were bombarded by lithium, carbon and oxygen ions in the energy range from several hundred keV to several MeV. The induced surface structures were measured in the air with atomic force microscopy (AFM) in the tapping mode. The hillock-like structure on the mica surface was observed. The height of the hillock increases linearly when the energy loss is above 1.2 keV/nm. The induced structures are similar with the similar electronic stopping powers but different projectiles for muscovite mica.
- Published
- 2013
13. Transmission of 16keV Cu− ions through Al2O3 nano-capillaries
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Jianxiong Shao, Ximeng Chen, Lin Chen, Xueyang Lv, Juanjuan Jia, Peng Zhou, Mingchao Ji, Zhou Chunlin, and Hong-Wei Wang
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Nuclear and High Energy Physics ,Quantitative Biology::Neurons and Cognition ,Capillary action ,Chemistry ,Nano ,Analytical chemistry ,Ion current ,Microchannel plate detector ,Charge (physics) ,Electron ,Instrumentation ,Charge exchange ,Ion - Abstract
The interaction of 16 keV Cu − ions with Al 2 O 3 nano-capillaries of 50 nm diameter and 10 μm length was studied. The angular and charge state distributions of the transmitted particles were measured by a position-sensitive microchannel plate detector. It shows that transmitted particles appear as two peaks and consist of three charge states, Cu − , Cu 0 and Cu + . As the tilt angle increases, more Cu − ions lose electrons resulting in the formation of Cu 0 and Cu + during multiple collisions with the capillary walls. Unlike previously reported results on highly charged ions, keV-energy Cu − ions undergo significant charge exchange processes with the inner walls of the capillaries. This indicates that the guiding effect is absent in the negative ion transmission under the very low ion current conditions.
- Published
- 2012
14. Single electron loss in the collisions of lowly charged ions and atomic hydrogen
- Author
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Xiaoping Ouyang, Weifeng Ni, Guanghui Su, Huiping Liu, and Ximeng Chen
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Nuclear and High Energy Physics ,Range (particle radiation) ,Hydrogen ,Electron capture ,Projectile ,chemistry.chemical_element ,Electron ,Ion ,Single electron ,medicine.anatomical_structure ,chemistry ,medicine ,Atomic physics ,Nuclear Experiment ,Instrumentation ,Nucleus - Abstract
In this paper, the projectile electron loss cross sections of He+, Li+, Li2+ and C2+ colliding with atomic hydrogen are studied in the frame work of the extended over-barrier model at intermediate velocities (25–600 keV/u). The electron loss cross sections are calculated in terms of the interaction between the screened target nucleus and the active projectile electron and of the interaction between the projectile electron and the target electron. Compared with the measurements, this model satisfactorily reproduces the experimentally obtained energy dependence of the single electron loss cross sections over the energy range investigated here.
- Published
- 2010
15. Molybdenum L-shell X-ray production by 350–600keV Xeq+ (q=25–30) ions
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Ximeng Chen, Jianxiong Shao, X.H. Zhang, Yange Zhang, Jinzhang Xu, Hao-Li Zhang, Ying Cui, Zou Yang, G.Q. Xiao, and Yongtao Zhao
- Subjects
Nuclear and High Energy Physics ,Projectile ,X-ray ,chemistry.chemical_element ,Kinetic energy ,L-shell ,Ion ,chemistry ,Molybdenum ,Ionization ,Physics::Atomic and Molecular Clusters ,Coulomb ,Atomic physics ,Instrumentation - Abstract
Molybdenum L-shell X-rays were produced by Xeq+ (q = 25-30) bombardment at low energies from 2.65 to 4.55 keV/amu (350-600 keV). We observed a kinetic energy threshold of Mo L-shell ionization down to 2.65-3.03 keV/amu (350-400 keV). The charge state effect of the incident ions was not observed which shows that the ions were neutralized, reaching an equilibrium charge state and losing their initial charge state memory before production of L-shell vacancies resulted in X-ray production. The experimental ionization cross sections were compared with those from Binary Encounter Approximation theory. Taking into account projectile deflection in the target nuclear Coulomb field, the ionization cross section of Mo L-shell near the kinetic energy threshold was well described. (C) 2010 Published by Elsevier B.V.
- Published
- 2010
16. Polarization effects on the cross-section of ion–atom collisions
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Ying Cui, Y.X. Lu, L.J. Liu, D.T. Xiao, T. Yu, Ximeng Chen, and Jianxiong Shao
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Nuclear and High Energy Physics ,Neon ,chemistry ,Tunnel ionization ,Electron capture ,Ionization ,Atom ,chemistry.chemical_element ,Electron ,Atomic physics ,Impact parameter ,Instrumentation ,Ion - Abstract
Coupled-channel cross-sections for electron capture, ionization and electron loss due to polarization effects are calculated. The maximum impact parameter for electron escape is analyzed within the classical framework. The probabilities of ionization and capture are analyzed simultaneously by a semi-empirical method. Differing from the n-body classical trajectory Monte Carlo method, the condition for electron escape is determined by Coulomb forces related to the two nuclei. This method can be used to calculate coupled-channel cross-sections rather than single-channel ones in other methods. Therefore the calculated results can be compared with experimental data directly. In the low energy range, neglecting the ionization effect, the single-capture cross-sections of hydrogen atoms induced by various partially-stripped ions were calculated. In the high energy range, neglecting the capture effect on ionization, the pure-ionization cross-sections of neon atoms induced by Ne q + ( q = 4, 6, 8) and Ar q + ( q = 4, 6, 8, 10) at an incident energy E = 1.05 MeV/u were calculated. Good agreement was found between our calculation and experimental data in the literature. This method had been partially applied for intermediate energy successfully.
- Published
- 2009
17. An outlook of heavy ion driven plasma research at IMP-Lanzhou
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Pengming Zhang, Guoqing Xiao, Jiawen Xia, Zhongfeng Xu, Fuli Li, Di Zhao, Huan-Yu Zhao, Yongtao Zhao, Zhihu Yang, Xinwen Ma, Wenlong Zhan, Deihui Li, Ximeng Chen, Hu-Shan Xu, Yong Liu, Gen-Ming Jin, Hongwei Zhao, and Yuyu Wang
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Nuclear physics ,Nuclear and High Energy Physics ,Chemistry ,Energy density ,Physics::Accelerator Physics ,Heavy ion ,Plasma ,Successful completion ,Instrumentation ,Beam (structure) ,Storage ring - Abstract
Since the successful completion of the cooling storage ring (CSR) project in China at the end of 2007, high qualitative heavy ion beams with energy ranging from keV to GeV/u have been available at the Heavy Ion Research Facility at Lanzhou (HIRFL). More than 10 9 1 GeV/u C 6+ particles or 10 8 235 MeV/u Xe particles can be stored in the CSR main-ring and extracted within hundred nano-seconds during the test running, the beam parameters will be improved in the coming years so that high energy density (HED) conditions could be achieved and investigated there. Recent scientific results from the experiments relevant to plasma research on HIRFL are summarized. Dense plasma research with intense heavy ion beams of CSR is proposed here.
- Published
- 2009
18. Pure ionization cross section of helium and ionization mechanism
- Author
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YuWen Liu, Juan Du, Zhi-Min Gao, Y.X. Lu, Ximeng Chen, and Ying Cui
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Nuclear and High Energy Physics ,Cross section (physics) ,Projectile ,Chemistry ,Ionization ,chemistry.chemical_element ,Charge (physics) ,Atomic physics ,Molar ionization energies of the elements ,Instrumentation ,Helium ,Coincidence - Abstract
Pure target ionization was investigated for 0.4–6.4 MeV C q + ( q = 1–4) + He and O q + ( q = 1–4) + He collisions. The double-to-single target ionization ratios R 21 were measured using coincidence techniques. We compare our results with existing experimental results and find they are in good agreement. The ratio R 21 is nearly independent of projectile charge state. The relation of R 21 ∼ V is analyzed using the over barrier model (OBM) and ionization probability, which is described in our extended over barrier model. Our calculation agrees well with the experimental results.
- Published
- 2007
19. One and two electron transitions in multiply charged ions and helium collisions
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Ximeng Chen and Lin Chen
- Subjects
Nuclear and High Energy Physics ,symbols.namesake ,Atomic electron transition ,Chemistry ,Monte Carlo method ,symbols ,chemistry.chemical_element ,Atomic physics ,Instrumentation ,Helium ,Bohr model ,Ion - Abstract
In this paper, an extension of the already-developed and modified over-barrier model is presented to study theoretically one and two electron transitions between helium atoms and multiply charged ion collisions at a low-to-intermediate velocity (v(Bohr) similar to 5v(Bohr)). It is found that the present model can partially reproduce the experimentally obtained velocity dependence of the absolute cross-sections which is also supported by the results of the classical trajectory Monte Carlo (CTMC) method. (c) 2007 Elsevier B.V. All rights reserved.
- Published
- 2007
20. Double-to-single ionization ratios of helium bombarded by low-to-intermediate velocity Cq+, Oq+ (q=1∼3) ions
- Author
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Ying Cui, Juan Du, Ximeng Chen, Zhi-Min Gao, Jianxiong Shao, Baowei Ding, Y.X. Lu, YuWen Liu, and Hongbin Fu
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Nuclear and High Energy Physics ,chemistry ,Projectile ,Ionization ,Double ionization ,Physics::Atomic and Molecular Clusters ,Oxygen ions ,chemistry.chemical_element ,Atomic physics ,Collision ,Instrumentation ,Helium ,Ion - Abstract
We measured the double-to-single ionization ratios R of Helium bombarded by Cq+ and Oq+ ions (q = 1 ∼ 3). The velocity of the projectile varies from vBohr to 4 vBohr, the energy varies from 25 keV/amu to 500 keV/amu. The value of R increases rapidly with the collision velocity and reaches the maximum when the velocity is about 2 or 3 vBohr, then it decreases slowly for the higher velocity. A simple model is presented to estimate the value R varying with the collision velocity. The results calculated by the model are in agreement with the experimental data basically.
- Published
- 2007
21. X-ray emission of hollow atoms formed by highly charged argon and xenon ions below a beryllium surface
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Fuli Li, Zhihu Yang, Xiaoan Zhang, Wenlong Zhan, Guoqing Xiao, Ximeng Chen, Yongtao Zhao, and Yanping Zhang
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Nuclear and High Energy Physics ,Argon ,Xenon ,Chemistry ,Shell (structure) ,X-ray ,Electron shell ,chemistry.chemical_element ,Beryllium ,Atomic physics ,Instrumentation ,Spectral line ,Ion - Abstract
The X-ray emission induced by highly charged argon and xenon ions impinging on a beryllium surface is investigated. It is found that spectra of the X-ray induced by Ar 17,18+ interacting with the surface are very different from those of the X-ray induced by Ar 17,18+ interacting with residual gases. The result provides an experimental evidence for the existence of hollow atoms below the surface. Several unexpected X-ray lines are also found in the experiment. Firstly, K X-rays are observed when Ar 16+ ions which initially have no K shell holes interact with the surface. Secondly, if there are more than 2 M shell vacancies at the initial time, strong Mαα two-electron-one-photon (TEOP) transitions are found in the collisions of Xe 28+,29+,30+ ions with the surface.
- Published
- 2007
22. X-ray spectroscopy of hollow argon atoms formed on a beryllium surface
- Author
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Fuli Li, Yongtao Zhao, Guoqing Xiao, Zhihu Yang, Xiaoan Zhang, Ximeng Chen, and Wenlong Zhan
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Nuclear and High Energy Physics ,X-ray spectroscopy ,Argon ,Astrophysics::High Energy Astrophysical Phenomena ,Analytical chemistry ,Electron shell ,chemistry.chemical_element ,Electron ,Ion ,chemistry ,Physics::Plasma Physics ,Yield (chemistry) ,Physics::Atomic and Molecular Clusters ,Particle ,Physics::Atomic Physics ,Physics::Chemical Physics ,Beryllium ,Instrumentation - Abstract
The X-rays induced during interaction of highly charged argon ions with a beryllium surface are reported. It is found that the K shell X-ray yield of single particle during interaction of hydrogen-like argon ions was 3.6 × 10 −3 , which is five orders more than that of helium-like argon ions. Moreover, due to the screening the 2s electron, no K X-ray was emitted during interaction of lithium-like argon ions with the beryllium surface. It is also found that the X-ray spectrum induced by Ar 17+ interacting with residual gases is very different from that induced by Ar 17+ interacting with the surfaces, that provided an experimental evidence for the existence of the hollow atoms below the surface.
- Published
- 2006
23. Binding energy enhancement in the isocharge sequence of ions in collisions with Ne
- Author
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Xiaohong Cai, Zhurong Cao, Caojie Shao, Wei Yang, Ximeng Chen, Xinwen Ma, Rongchun Lu, and Deyang Yu
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Nuclear and High Energy Physics ,Single electron ,Projectile ,Chemistry ,Ionization ,Binding energy ,Atomic number ,Electronic structure ,Atomic physics ,Valence electron ,Instrumentation ,Ion - Abstract
The dependence of the ratio R-1 for transfer ionization to single capture for Cq+, Nq+, Oq+, Neq+ ions on Ne target upon the electronic structure of the projectile is studied by using position sensitive and time-of-flight techniques. It is found that for A(q+)-Ne collisions the ratio R-1 decreases as the atomic number of the projectile increases for q = 4, 5, 6, 7 sequences which differs' markedly from the results we obtained for A(q+)-Ar collisions. The difference is explained by using a statistical model and the orbital penetration picture. Comparison of the R-1 ratios of A(4+)-Ne and A(4+)-Ar collisions provides strong evidence for the increase of the binding energy of the target valence electron after single electron capture. The increase in binding energy depends both upon the atomic number of the projectile Z(1) and the target atom Z(2). The larger Z(1), the larger the increase in binding energy, while the larger Z(2), the smaller the increase in binding energy. (C) 2004 Published by Elsevier B.V.
- Published
- 2004
24. Ion guiding through capillaries in uncoated Al2O3 membranes
- Author
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Hongliang Liu, Fayuan Xi, Y. Wang, Y.X. Lu, and Ximeng Chen
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chemistry.chemical_classification ,Nuclear and High Energy Physics ,Range (particle radiation) ,Materials science ,Drift velocity ,Capillary action ,Nanotechnology ,Polymer ,Molecular physics ,Charged particle ,Ion ,Polyester ,Membrane ,chemistry ,Instrumentation - Abstract
We made an experimental study on ion guiding through capillaries in uncoated Al2O3 membranes using a variety of ions such as O1+, O3+, and O6+. The incident energy was varied within the range of 30-150 key. The results were compared with others using coated PET and Al2O3 capillary membranes as well as with the so-called scaling law discovered by Stolterfoht and his co-workers. Good agreement of our results with the scaling law was found. However, our membranes showed extraordinarily strong guiding ability. The reason lies in that our membranes were uncoated. A slower charge drift speed along the insulating capillary wall and a much larger equilibrium charge Q(infinity) seems to exist in our experiment. (c) 2010 Elsevier B.V. All rights reserved.
- Published
- 2010
25. Cross sections for transfer ionization in ion-helium collisions
- Author
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Deyang Yu, Ximeng Chen, and Baowei Ding
- Subjects
Nuclear and High Energy Physics ,Chemistry ,Ionization ,chemistry.chemical_element ,Atomic physics ,Instrumentation ,Helium ,Ion - Abstract
A simple model has been developed within the independent-particle model (IPM) based on the Bohr–Lindhard model and classical statistical model. Cross sections for transfer ionization of helium by ions A q + ( q = 1–3) are calculated for impact energies between 10 and 6000 keV/u. The calculated cross sections are in good agreement with the experimental data of helium by He (1–2)+ and Li (1–3)+ .
- Published
- 2008
26. One and two electron transitions in energetic ion and helium collisions
- Author
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Shengpeng Wang, Ziyong Shen, Xiao Cai, Z.Y. Liu, Xiu-Wen Ma, Ximeng Chen, and Kui Lu
- Subjects
Nuclear and High Energy Physics ,Electron capture ,Chemistry ,Atomic electron transition ,Ionization ,Double ionization ,Atom ,chemistry.chemical_element ,Atomic physics ,Instrumentation ,Electron ionization ,Helium ,Ion - Abstract
The single ionization (SI) and double ionization (DI), single and double ionization accompanying one electron loss (SS) of the projectile and the single and double electron capture of the projectile from target atom are investigated for 2.0–8.0 MeV Naq+–He and C1q+–He collisions. The cross-section ratio of the double ionization (DI) to that of the SI, the ratio of SS+DI to SS+SI, and ratio of double capture (DC) cross-section to that of single capture (SC), are measured by means of time-of-flight technique. The velocity and charge state dependences of the measured cross-section ratios are studied and discussed. The obtained capture cross-section ratios are compared with the theoretical calculations using the classical over-barrier model.
- Published
- 1998
27. The investigation of the multiple ionization of argon by energetic oxygen ions
- Author
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M.D. Hou, Ximeng Chen, Z.Y. Liu, H.P. Liu, X.W. Ma, Ziyong Shen, and Xu Cai
- Subjects
Nuclear and High Energy Physics ,Chemical ionization ,Physics::Instrumentation and Detectors ,Chemistry ,Thermal ionization ,Molar ionization energies of the elements ,Ion source ,Atmospheric-pressure laser ionization ,Physics::Plasma Physics ,Ionization ,Physics::Atomic and Molecular Clusters ,Physics::Atomic Physics ,Atomic physics ,Instrumentation ,Electron ionization ,Ambient ionization - Abstract
The cross section ratios of the double, triple and quadruplicate ionization to the single ionization of argon were measured by 1.5–7.5 MeV partially stripped oxygen ion (q = 1–4) bombardment. The Auger and the charge exchange processes are discussed and subtracted from the total multiple ionization ratios in order to study the mechanism of the direct multiple ionization of argon by partially stripped ions in the present energy range. It is found that the obtained ratios of the multiple ionization cross sections to those of the direct single ionization of argon agree well with the (νqeff)−2n+2 law for 1.5–7.5 MeV Oq+ (q = 1–4) impinging ions.
- Published
- 1996
28. The ionization of helium by 1.5–7.5 MeV partially stripped Cq+ ions
- Author
-
M.D. Hou, Xu Cai, Z.Y. Liu, Ximeng Chen, Ziyong Shen, H.P. Liu, and X.W. Ma
- Subjects
Nuclear and High Energy Physics ,Work (thermodynamics) ,Range (particle radiation) ,chemistry ,Projectile ,Ionization ,chemistry.chemical_element ,Charge (physics) ,Atomic physics ,Instrumentation ,Helium ,Effective nuclear charge ,Ion - Abstract
The double to single ionization cross section ratios of helium by partially stripped carbon ions have been measured for projectile charge states ranging from +1 to +4 and impact energies from 1.5 to 7.5 MeV. The effective charge effect in partially stripped ion-helium collision is presented. It is found that the effective charge qeff increases as the impinging energy increases and qeff shows a modest dependence upon the projectile charge state in the present energy range. The projectile charge state, projectile and target electronic state dependences of the effective charge effect is discussed using orbital interpenetrating. The nCTMC calculations were carried out to investigate the energy dependence of the effective charge. By introducing effective charge the cross section ratio of helium obtained in the present work is in good agreement with the ( V q eff ) −2 law.
- Published
- 1996
29. L-subshell ionisation of 71Lu, 73Ta and 79Au by 1.5–4.5 MeV alpha particles
- Author
-
X.W. Ma, Z.C. Chen, S.X. Ma, H.P. Liu, Q. Xu, Z.Y. Liu, X. Cai, and Ximeng Chen
- Subjects
Physics ,Nuclear physics ,Nuclear and High Energy Physics ,Ionization ,Elementary particle ,Alpha particle ,Atomic physics ,Inelastic scattering ,Instrumentation ,Spectral line ,Charged particle ,L-shell ,Ion - Abstract
The L X-rays of 71 Lu, 73 Ta and 79 Au were produced by 1.5–4.5 MeV alpha particle bombardment. The emitted L α , L γ1 and L γ2,3 lines were selected to convert X-ray production cross sections into ionisation cross sections. The ionisation cross sections obtained were compared with the predictions of the ECPSSR theory. A reasonable agreement of L 3 -subshell ionisation cross sections between the present experiment and the ECPSSR theory is found. The departures of the measured L 2 -subshell ionisation cross sections from the ECPSSR theory are discussed.
- Published
- 1992
30. Multiple ionization of argon by 170 MeV S9+ ions
- Author
-
Kui Lu, Zhihu Yang, Zhaoyuan Liu, Xiaohong Cai, Xinwen Ma, Ximeng Chen, Ziyong Shen, Huiping Liu, and Youde Wang
- Subjects
Nuclear and High Energy Physics ,Argon ,Physics::Instrumentation and Detectors ,Chemistry ,Projectile ,Monte Carlo method ,chemistry.chemical_element ,Ion source ,Ion ,Recoil ,Physics::Plasma Physics ,Coincident ,Ionization ,Physics::Atomic Physics ,Atomic physics ,Nuclear Experiment ,Instrumentation - Abstract
Multiple ionization in collisions of 170 MeV S9+ ions on Ar target atoms was investigated by using time-of-flight (TOF) technique. The charge state distribution of the recoil ions produced in the collisions were determined by the coincident TOF between the projectiles and the recoil ions. The relative recoil ion productions were extracted and compared with the theoretical calculations of n-body classical trajectory Monte Carlo methods.
- Published
- 1998
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