Ar的类氦和类锂离子与Mo表面相互作用过程中的x射线发射

在兰州重离子加速器国家实验室电子回旋共振离子源上用Si(Li)探测器观测到了不同动能的Ar¹⁵⁺和Ar¹⁶⁺离子与Mo表面相互作用过程产生的x射线.在不同动能 的Ar¹⁶⁺与Mo表面作用过程中不仅能观测到Ar的K层x射线而且能观测到Mo的L层x 射线.在不同动能的Ar¹⁵⁺入射下只能观测到Mo的L层x射线.实验结果表明，Ar的 K层x 射线的产额与入射离子的动能、作用过程中形成的空心原子携带的势能以及入射离子和靶原 子x射线的竞争等有关，Mo的L层x射线随入射离子动能的增加而增加. 关键词： x射线发射 高电荷态离子 Mo表面     

Ar16+和Ar17+离子与Zr作用产生的X射线谱

将超导离子源提供的10—20keV/q Ar¹⁶⁺和Ar¹⁷⁺离子入射到Zr金属表面,在相互作用中产生的X射线谱表明,高电荷态Ar¹⁶⁺离子在金属表面中性化过程中有可能存在多电子激发,使Ar¹⁶⁺的K壳层电子被激发形成空穴,在退激过程中发射特征Kα-X射线.空心原子Ar的K层发射X射线强度随入射离子的动能而减弱,靶原子Zr的L壳层发射X射线强度随入射离子动能的增加而增强.Ar¹⁷⁺的单离子的Kα- 关键词： 高电荷态离子 空心原子 X射线     

K-shell ionization cross section of aluminium induced by low-energy highly charged argon ions

Al K-shell X-ray yields are measured with highly charged Ar^q+ ions (q=12–16) bombarding against aluminium. The energy range of the Ar ions is from 180 to 380 keV. K-shell ionization cross sections of aluminium are also obtained from the yields data. The experimental data is explained within the framework of 2pπ -2pσ rotational coupling. When Ar ions with 2p-shell vacancies are incident on aluminium, the vacancies begin to reduce. Meanwhile, collisions against Al atoms lead to the production of new 2p-shell vacancies of Ar ions. These Ar 2p-shell vacancies will transfer to the 1s orbit of an Al atom via 2pπ-2pσ rotational coupling leading to the emission of a K-shell X-ray of aluminiun. A model is constructed based on the base of the above physical scenario. The calculation results of the model are in agreement with the experimental results.     

Two Electron Transfer and Stabilization in Slow O^6＋ and Rare-Gas Collisions

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     

X-Ray in Highly Charged Ar17+Ion Interacting with Mo Surface

The X-ray emission from the highly charged Ar¹⁷⁺ ion interacting with Mo surface are measured on the 14.5GHz Electron Cyclotron Resonance ion source facility at Institute of Modern, the Chinese Academy of Sciences in Lanzhou. Ar¹⁷⁺ ions came from Electron Cyclotron Resonance ion source and impacted on Mo surface.The incident ion with vacancy of inner shell captures electrons emitted from surface into highly excited Rydberg states, outer shell electron cascades into K vacancy giving rise to Kα X-ray emission of the incidentionsions.     

Absolute measurement of sputtered ion fractions using matrix isolation spectroscopy

Sputtering yields for neutrals and ions have been measured by collecting the sputtered species in a noble gas matrix and determining their amounts from optical absorption spectroscopy. The atomic ion fractions for Ti and Zr bombarded by O₂⁺ at 2 keV are 0.8 and 0.4, respectively, whereas TiO and ZrO are sputtered largely as neutrals. Neutral sputtering yields from Ar⁺ bombardment arc consistent with previous measurements. The experimental results are compared with various theoretical models for the sputtering process.     

Kinetic energy and charge state effects in the X-ray emission of Mo surface induced by Xe q + ( q = 25, 29) ions

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     

A new technique for the measurement of sputtering yields

We have measured the yields of 90 keV ⁴⁰Ar⁺ and V⁴He⁺ sputtering of Mo and V samples by the use of a new radio-tracer technique. This technique involves activating the samples by high-energy charged-particle irradiation before sputtering, and using conventional γ-ray counting methods to analyze the material subsequently sputtered onto collector foils. We have also measured angular distributions of the sputtered material, and compared these results and our total sputtering yields with the predictions of Sigmund's sputtering theory. Further comparisons between our radiotracer results and those obtained for ⁴⁰Ar⁺ sputtering of unactivated Mo and V samples, determined from elastic backscattering measurements using 12 MeV ¹⁶O ions, show that the techniques give consistent results.     

Mo/Si体系的离子束混合机制研究

本文采用卢瑟福背散射(RBS)分析技术详细测量了Mo/Si体系在Ar⁺和Xe⁷⁺离子束轰击下界面混合和反应随温度、剂量和剂量率的依赖关系。得到了许多新的结果。结果表明,以前的空位扩散机制、单级联间隙原子扩散机制和热峰模型都不能解释Mo/Si体系的离子束混合。我们结合固体扩散理论提出了间隙原子扩散和反应机制,圆满地解释了实验结果。 关键词：     

Ionizing Dose Effect of Thermal Oxides Implanted with Si^＋ Ions

Total ionizing dose effects of Si^＋ ion implanted thermal oxides are studied by 10keV x-ray irradiation. Photoluminescence （PL） method is engaged to investigate nanostructures of samples. Ar^＋ implanted samples are also studied by the same way to provide a comparison. The results show that Si^＋ implantation following with high temperature annealing can significantly reduce the radiation induced flatband shift, which is caused by net posi- tive charge accumulation in oxides. This reduction is attributed to the formation of Si nanoscale structures. Ar^＋ implantation is also found to reduce the radiation induced flatband shift, while it is different that the reduction with Si^＋ implantation shows little dependence on implant dose of Ar^＋ ions. This is explained by possible increase of recombination centres.     

低能高电荷态Arq+(q=12,13)离子诱发钼L壳层X射线强度的研究

本文报导了低能高电荷态Arq (q=12,13)离子诱发的钼L壳层X射线强度随入射粒子能量的变化趋势,研究表明当入射粒子能量高于220 keV时,钼L壳层X射线强度有明显增加的的趋势.同时,我们提出了一个简单的模型去估计这种趋势随入射能量的变化.模型计算的结果与实验值符合的比较好.     

H+和Ar11+激发Si的K壳层X射线发射研究

测量了50–250 keV H⁺和1.0–3.0 MeV Ar¹¹⁺ 轰击Si表面过程中辐射的X射线. 结果表明, 在Ar¹¹⁺入射的情况下, 引起了Si的L壳层上3, 4个电子的多电离.计算了Si的K壳层X射线产生截面, 并将两体碰撞近似(BEA), 平面波恩近似, ECPSSR理论计算与实验值进行了对比. ECPSSR理论与质子产生的截面数据能够很好地符合; 而考虑多电离后, BEA理论与Ar¹¹⁺的实验结果符合较好. 关键词： X射线 高电荷态重离子 多电离     

Sputtering experiments with silver single crystals and the channeling phenomena

Sputtering yields of monocrystalline silver under irradiation with 7-30 keV Ar⁺, Kr⁺ and Xe⁺ ions, not reported earlier, have been determined. The yield has been found to depend strongly on the orientation of the crystal and mass of the impinging ion. Onderdelinden's model based on Lindhard's theory of Channeling is found to describe satisfactorily, the observed orientation and ion-mass dependence of the yields for the ions of energy ～10 keV or above. The role of the barrier potential approximated in the model in predicting the experimental results is discussed.     

Neutralization and Detachment in H^＋-H^- Collisions

The cross sections for neutralization and detachment in H^＋-H^- collisions in the energy range from 1.0 to lOO keV/u are calculated using the two-centre atomic orbital close-coupling （TC-AOCC） method. The results are compared with the available experimental and theoretical data. It is found that the neutralization cross section agrees well with the experimental data by Schon et al. [3. Phys. B 20 （1987） L759] and Melchert et al., [J. Phys. B 32 （1999） L139] especially at low energies. However, for the detachment process, our calculated cross section lies between the experimental data by Melchert et al. and by Peart et al. [J. Phys. B 9 （1976） 3047] for the energy below 15keV/u. Above this energy, our result is smaller than the two experimental data. It is worth pointing out that there exists a large difference between these two experimental data and it is difficult to judge which data is more accurate. Therefore, a high-precision measurement for detachment cross sections is expected to resolve this discrepancy and to test the theoretical calculations.     

X-ray spectra induced by slow highly charged Ar q + ions in collision with Nb surface

The X-ray spectra of Nb surface induced by Ar ^q+ (q = 16,17) ions with the energy range from 10 to 20 keV/q were studied by the optical spectrum technology. The experimental results indicate that the multi-electron excitation occurred as a highly charged Ar¹⁶⁺ ion was neutralized below the metal surface. The K shell electron of Ar¹⁶⁺ was excited and then de-excited cascadly to emit K X-ray. The intensity of the X-ray emitted from K shell of the hollow Ar atom decreased with the increase of projectile kinetic energy. The intensity of the X-ray emitted from L shell of the target atom Nb increased with the increase of projectile kinetic energy. The X-ray yield of Ar¹⁷⁺ is three magnitude orders larger than that of Ar¹⁶⁺. Supported by the National Natural Science Foundation of China (Grant Nos.10774149 and 10405025)     

Electron multiplicity in slow collisions of Ar ions with C

Electron capture by Ar⁸⁺ in collisions with C₆₀ fullerene has been investigated using coincident measurements of the number n of ejected electrons, the mass and charge of multicharged Cr+ ₆₀ recoil ions and their fragments Ci+ m and the final charge state of outgoing projectiles Ar(8-s)+ (). The number of captured electrons r is the sum of the numbers of stabilized and emitted electrons: r = n + s. The ratio n / s decreases by a factor three with s increasing from 1 to 7 showing that the multiply excited states populated by capture of a large number of electrons are rather stable against auto-ionisation. Each kinetic energy spectrum of Ar⁺ and Ar²⁺ projectiles is composed of two peaks which we attribute to collisions “inside” and “outside” the C₆₀ cage. The measured energy shift of the projectile keV is consistent with the corresponding energy loss keV in a carbon foil with an equivalent thickness. Inside collisions are characterized by a strong dissociation of recoil ions into light monocharged fragments and by a high multiplicity of ejected electrons. Received: 25 March 1998 / Received in final form and Accepted: 9 June 1998     

Radiation damage of material surfaces under prolonged irradiation with He+ and Ar+ ions with broad energy spectra

The results of studying the redistribution of Be, Al, Ti, Fe, Cu, Zr, Mo, and W atoms incorporated in polycrystalline metal samples under irradiation with He⁺, (He⁺ + Ar⁺), and Ar⁺ ion beams with a broad energy spectrum and an average energy of 10 keV at irradiation doses of 1 × 10²¹ ion/cm² are studied. It is discovered that irradiation at doses exceeding 1 × 10¹⁹ ion/cm² results in local small-crystal formations being produced in a near-surface substrate layer. Their typical dimensions are less than 1–5 μm, and their the density is up to 1–100. They contain incorporated atoms and impurity atoms with a concentration of 0.1–10 at %. Subsequent irradiation at a dose of 1 × 10²⁰ ions/cm² or more leads to disappearance of these formations, mainly because of sputtering processes.     

Photon emission from rare gas ion bombardment of metal surfaces

Metal surfaces (Mg, Cu, Zr, Mo) are bombarded with He⁺, Ne⁺ and Ar⁺ in the energy range of 400 eV to 8 keV. Radiation from scattered projectiles and sputtered target particles is observed between 200 and 700 nm. It is shown that most of the radiating particles originate from surface collisions. Auger neutralization, resonance tunneling and direct electron transitions are the important electronic processes involved.     

Inner-shell ionization by positron and electron impact

Measurements of relative cross sections of K- and L-shell ionization of silver and gold targets by positron and electron impact at projectile energies of 30–70 keV are reported. The experiments were performed at the slow positron source TEPOS at the linac of the Strahlenzentrum. This source and the experimental equipment will be described briefly and the experimental results will be presented in detail. In addition, plane wave Born (PWBA) calculations were performed. They include an electron exchange term and the deceleration or acceleration of the incident projectile in the nuclear field of the target atom. The present experimental results agree well with these calculations; for L-shell ionization, they are at variance with a previous experiment where a different energy dependence was observed.     

Argon L-shell Auger spectra produced in Ar+ -Ar collisions

Argon L-shell Auger spectra were measured by 100 to 550 keV Ar⁺ impact on Ar. Observed line structure in the spectra are interpreted both by multiple outer-shell ionization and Doppler effects.