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采用蒙特卡罗模拟方法,对低速高电荷态Ar~(q+)离子掠射到单晶铜表面时的能损谱与表面结构的依赖关系进行研究。在能损计算中,包含了四种可能的能损机制。对于Ar原子沿着晶列方向掠射时,发现能损谱为一两峰结构,其中在能损比较大的区间新出现一个明显的小峰结构。通过研究Ar~(q+)以不同条件掠射到表面的能损,对观察到的沟道效应进行论述。能损谱的计算结果与实验结果吻合得比较好。 相似文献
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刘之景 《原子与分子物理学报》2000,17(2):251-255
采用二体碰撞近似和托马斯 -费米近似计算了多电荷离子18Arq+( q =3,4 )与中性原子H和He碰撞的电荷剥离截面以及Arq+的势函数和电子动量分布 ,计算结果与文献 [4]中的数据符合得较好。所导出的计算公式和编制的计算程序可以计算任何一个多电荷离子Aq +与H或He碰撞的电荷剥离截面。因而具有一定的普适性。 相似文献
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研究了两个偶极相互作用二能级原子与高Q腔场双光子相互作用的腔场谱.给出了初始光场为Fock态、相干态和压缩真空态时的计算结果并解释了谱结构的形成,分析了原子间的偶极相互作用和初态的交换对称性对腔场谱的影响.发现当两原子均处于激发态时,腔场谱只在初始光场为真空态时出现4峰结构,而在其它初始场时,都呈现出奇数峰,这与相应的辐射谱偶数峰的结构明显不同.而两原子只有一个处于激发态时,腔场谱结构主要由原子初态是否具有交换对称性决定.
关键词: 相似文献
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耦合双原子Jaynes-Cummings模型的腔场谱H 总被引:14,自引:8,他引:6
研究了处于激发态的两原子与高Q腔场相互作用单光子过程的腔场谱,给出了初始光场为光子数态、相干态、压缩真空态时的腔场谱数值计算结果,分析了原子间偶极-偶极相互作用强度gα对腔场谱结构的影响.发现真空场Rabi峰,当gα较弱时为4峰,gα较强时为3峰结构;弱场数态(n>0)时为5峰,强场时为3峰结构.相干态和压缩真空态时,谱结构与光子数分布有关,一般为复杂的多峰结构.结果表明,gα对峰位峰高都有影响,破坏了谱结构的对称性,但这种影响只在真空场和弱场时才较明显. 相似文献
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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
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本文使用密度泛函理论研究了熔石英中peroxy linkage(POL)缺陷和中性氧空位(NOV)缺陷的几何结构,电子结构以及光学性质.采用自洽的准粒子GW计算结合求解Bathe-Salpeter方程的多体理论,研究了缺陷引起的电子结构和光学吸收谱的变化.首先研究了无缺陷非晶结构的电子结构与吸收谱,得到的结果与实验值非常接近.对POL的计算表明,其在基态下的局部结构与过氧化氢分子类似.采用多体理论计算得到的吸收谱表明其最低吸收峰位于6.3 eV处.这一结果不支持实验认为的位于3.8 eV处的吸收峰是由POL缺陷导致的说法.对于NOV缺陷,计算表明其基态的Si—Si键长为2.51?而三重态下的值则为3.56?.相应的GW+BSE计算表明中性氧空位缺陷导致了位于7.4 eV处的吸收峰,与实验测量结果一致. 相似文献
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ZHANG Xiao'an XIAO Guoqing YANG Zhihu CHEN Ximeng ZHAO Yongtao LI Fuli ZHANG Yinping CUI Ying ZHANG Hongqiang XU Xu SHAO Jianxiong ZHAN Wenlong 《中国科学G辑(英文版)》2006,49(2)
By use of optical spectrum technology, the spectra of X-ray induced by highly charged 40Arq+ ions interacting with Au surface have been studied. The results show that the argon Kα X-ray were emitted from the hollow atoms formed below the surface. There is a process of multi-electron exciting in neutralization of the Ar16+ion, with electronic configuration 1s2 in its ground state below the solid surface. The yield of the projectile Kα X-ray is related to its initial electronic configuration, and the yield of the target X-ray is related to the projectile kinetic energy. 相似文献
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A code has been developed to simulate the neutralization and grazing process of slow highly charged ion Xe^q+ on Al(111) surface under the classical-over-the-barrier model. The image energy gain of Xeq+ ions are calculated and compared with experiment data. The simulation results of image energy gain are in good agreement with the experiment data. Meanwhile, in the present work, the reflection coefficient of incident Xe^q+ on Al(111) surface as a function of the incidence angle, energy and charge state is also studied. 相似文献
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B. Bahrim A. G. Borisov D. Teillet-Billy J. -P. Gauyacq F. Wiegershaus St. Krischok V. Kempter 《Surface science》1997,380(2-3):556-567
The dynamics of nitrogen collisions with metals partially covered by alkali atoms is studied both experimentally and theoretically. Our attention focuses on the formation of N−(1D) metastable ions and their interaction with the surface. We present the electron energy spectra induced by slow collisions of N+ ions with partially cesiated Pd(111) surfaces under grazing incidence. These spectra display, as a function of Cs coverage, a sharp feature which is due to the autodetachment of N−(2p4, 1D) to the N(2p3, 4S) ground state. Our calculations, performed with the coupled angular mode (CAM) method on the basis of the resonant electron exchange between the nitrogen atom in states of the 2p3 configuration and the metal surface, consistently explain how negative ions formed close to the surface can survive against electron loss to the metal during the outgoing trajectory and can later decay as free ions. In order to understand the alkali coverage dependence of the N−(1D)-N(4S) peak intensity, the local character of the nitrogen interaction with the surface partially covered by adsorbate atoms has been taken into account. 相似文献
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Ying Cui ShengSheng Yang ZhiHu Yang JinZhang Xu HongQiang Zhang Xu Xu JianXiong Shao ZhaoYuan Liu GuoQing Xiao XiaoAn Zhang YongTao Zhao YanPing Zhang XiMeng Chen 《中国科学G辑(英文版)》2008,51(9):1240-1244
L-shell X-ray spectra of Mo surface induced by Xe25+ and Xe29+ were measured. The X-ray intensity was obtained in the kinetic energy range of the incident ions from 350 to 600 keV. The
relationship of X-ray intensity with kinetic energy of the projectile and its charge state were studied, and the simple explanation
was given.
Supported by the Science and Technology Ministry Foundation of China (Grant No. 2002CCA00900) and the Foundation of National
Key Laboratory of Vacuum & Cryogenics Technology and Physics 相似文献
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Angle-resolved electron energy spectra induced by bombardment of a Ni(100) monocrystal surface with 0.5–4.5 keV energy K+ ions have been measured. In the case when the target is previously implanted by K+ ions a peak (discrete structure) in the energy range 15 < E < 17 eV is observed. This phenomenon has been ascribed to deactivation of M23, vacancies of the K atom formed in the symmetrical collisions of projectiles with implanted or adsorbed surface K atoms. The phenomenon of the peak splitting at the higher projectile energies has been discussed within the frame of the Doppler effect in the specific case of symmetrical K-K collisions, where both collision participants can appear as Auger electron emitters. 相似文献
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S. W. Tong M. K. Fung C. S. Lee Y. Lifshitz S. T. Lee A. Hoffman 《Applied Surface Science》2003,220(1-4):19-25
Surface chemical composition of fluorocarbon films deposited onto indium-tin-oxide (ITO) substrates was modified by 2.0 keV Ar+ irradiation with doses of up to 2.6×1013 ions/cm2. The effect of ion irradiation on the chemical composition and bonding configuration of the upper-surface and sub-surface regions were monitored by high-resolution angle-resolved X-ray photoelectron spectroscopy (AR-XPS). It was found that the as-deposited films compose of a distribution of CF, CF2, CF3 and C–C chemical states. C 1s line-shape analysis of XPS spectra measured at grazing and normal emission angles shows that as a result of the irradiation, the population of the CF3 and CF2 chemical states were preferentially depleted from the film’s surface resulting in an increased population of the CF and C–C chemical states in the upper-surface region of the film. It is suggested that low energy ion irradiation can be used to chemically modify the surface of fluorocarbon films. 相似文献
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The total energy loss of N^+q ions (for v 〈 Bohr velocity) grazing on the Al(111) has been simulated without any 'fit' parameter and compared with the experimental data. The energy loss due to the charge exchange, happening before the N^+q hits the Al(111) surface, is studied. The present simulation shows that the energy loss strongly depends on the charge state of the projectile and the lattice orientation of Al(111) surface. The calculated total energy loss agrees with experimental data very well. 相似文献
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研究了高电荷态离子Arq+(q=16,17,18)入射金属Be,Al,Ni,Mo,Au靶表面产生的X射线谱.实验结果表明,Ar的Kα-X射线是离子在与固体表面相互作用过程中固体表面之下形成空心原子发射的.电子组态1s2的高电荷态Ar16+离子在金属表面中性化过程中,存在的多电子激发过程使Ar16+的K壳层电子激发产生空穴,级联退激发射Ar的Kα 特征X射线.Ar17+离子在金属表面作用过程中产生的X射线谱形与靶材料没有明显的关联,入射离子的Kα-X射线产额与其最初的电子组态有关,靶原子的X射线产额与入射离子的动能有关.
关键词:
高电荷态离子
空心原子
多电子激发
X射线 相似文献
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ZHANG Xiao’an ZHAO Yongtao LI Fuli YANG Zhihu XIAO Guoqing & ZHAN Wenlong .Department of Applied Physics Xi’an Jiaotong University Xi’an China .Institute of Modern Physics Chinese Academy of Sciences Lanzhou China 《中国科学G辑(英文版)》2004,47(6)
1 Introduction It has been found that a large number of ions and atoms can be sputtered; and elec-trons and X-ray can be emitted in the impact of slow highly charged ions (SHCI) onmetal surfaces. It has also been shown that a slow highly charged ion can deposit anamount of potential energy ranging from tens to hundreds of keV within a nanometer-sized volume on femtosecond time scale during impinging on a solid surface. Theequivalent power density is about 1014 W/cm2 and bombardment craters … 相似文献
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S. Lederer H. Winter HP. Winter F. Aumayr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):505-511
The energy loss of hydrogen atoms with energies of 400
eV and 1 keV is studied in coincidence with the number of emitted
electrons during grazing scattering from atomically clean and flat
KI(001) and LiF(001) surfaces. The energy loss spectra for
specific numbers of emitted electrons are analyzed in terms of a
binary interaction model based on the formation of transient
negative ions via local capture of valence band electrons from
anion sites. Based on computer simulations we derive for this
interaction scenario probabilities for the production of surface
excitons, for electron loss to the conduction band of KI, for
emission of electrons, and for formation of negative hydrogen
ions. The pronounced differences of data obtained for the two
surfaces are attributed to the different electronic structures of
KI and LiF. 相似文献