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1.
根据南京大学最近在离子簇结构和性质方面的研究进展,重点讨论离子簇的幻数和同位素效应及其与稳定结构和电荷状态的联系。离子簇(原子簇)是极小的原子聚合物,是介于固态和气态之间的物质状态,具有一系列奇异的性质。 相似文献
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根据南京大学最近在离子簇结构和性质方面的研究进展,重点讨论离子簇的幻数和同位素效应及其与稳定结构和电荷状态的联系。离子簇(原子簇)是极小的原子聚合物,是介于固态和气态之间的物质状态,具有一系列奇异的性质。 相似文献
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研究了LiF加入LiCl-KCl熔盐对钆电化学及络合行为的影响,发现LiF加入LiCl-KCl熔盐后,钆、铽的还原电位差由原来的6mV变为67mV。利用电化学方法和光谱方法研究了熔盐中钆离子和铽离子的配位结构,发现LiCl-KCl-GdCl_3(5mol%)/TbCl_3(5mol%)熔盐中存在[GdCl_6]~(3-)、[TbCl_6]~(3-)的正八面体结构;考察了LiF加入LiCl-KCl熔盐对钆、铽离子结构的影响,在LiCl-KCl-GdCl_3/TbCl_3中加入LiF后,钆离子和铽离子配位结构均为络合了3个F~-和3个Cl~-的八面体结构[GdF_3Cl_3]~(3-)和[TbF_3Cl_3]~(3-),计算得到两种八面体结构的相对累积稳定常数分别为10.98和6.38。以此为理论基础,进行了LiF对LiCl-KCl熔盐中钆电解精炼的影响研究,发现将LiF加入LiCl-KCl熔盐后进行钆电解精炼时,能以更高的去污系数分离钆。 相似文献
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《中国原子能科学研究院年报》2017,(0)
正电解精炼已成为干法后处理的首选技术路线,因此研究离子在熔盐中的电化学行为对干法后处理尤为重要。本工作测定了LiF加入LiCl-KCl熔盐前后对钆、铽还原电位的影响,发现加入LiF后钆、铽的还原电位差由原来的6mV变为67mV,增大了11倍多。用电化学和光谱的方法得到了熔盐中离子的配位结构,发现在LiCl-KCl-GdCl_3(5mol%)/TbCl_3(5mol%)熔盐中为[GdCl_6]~(3-)、[TbCl_6]~(3-)的正八面体结构,其拉曼图谱如图1所 相似文献
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研究了3种不同剂量He+离子辐照后Inconel 718合金的形貌变化规律及其形成机理。结果表明,He+离子辐照会在合金表面形成纳米多孔结构,其孔径会随辐照剂量的增加而增大。此外,He+离子辐照还会破坏合金表面δ相并导致碳化物的持续溅射损耗,且这一现象会随着辐照剂量的增加而愈发严重。由于辐照过程中氦泡间微观应力σ n作用会引起毗邻材料断裂及氦泡合并长大,且辐照溅射作用又会导致氦泡上层薄膜的损耗甚至破裂,因而这也是He+离子辐照Inconel 718合金表面纳米多孔结构的形成机制。 相似文献
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A.K. Dauletbekova A.T. Akilbekov M.V. Zdorovets A.F. Vassil’eva D.A. Akilbekova 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(19):3005-3008
Single LiF crystals were irradiated with Xe (195 MeV), Kr (117 MeV), and N (18 MeV) ions. Using absorption spectroscopy, color center creation was analyzed as a function of the ion energy loss, fluence, and flux. The concentration of single F centers and F2 centers versus fluence and flux exhibits a nonlinear evolution with saturation at higher fluences. For LiF irradiated with N ions at high fluence, the concentration of F centers is proportional to the cube root of the flux indicating the strong interaction of primary hole centers. Macroscopic hillocks were observed in all irradiated LiF crystals by atomic force microscopy. 相似文献
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A study on the interactions of high intensity (- 10^16 W/cm^2) femtosecond laser pulses with rare gas clusters in a dense jet is performed. Energy absorption by Ar and Xe clusters is measured and it can be as high as 90%. Very energetic ions produced in the laser interaction with a dense cluster jet are detected by time-of-flight spectrometry and the maximum ion energy of Xe is up to 1.3 MeV. The average ion energies are found to increase with increasing cluster size and get saturated gradually. The average ion energies also show a strong directionality and the average ion energy in the direction parallel to the laser polarization vector is 40% higher than that perpendicular to it. The findings are discussed in terms of a model of charge-dependent ion acceleration. 相似文献
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《Fusion Engineering and Design》2014,89(9-10):2235-2240
Thermoluminescence detectors (TLD) were used for dose measurements at JET. Several hundreds of LiF detectors of various types, standard LiF:Mg,Ti and highly sensitive LiF:Mg,Cu,P were produced. LiF detectors consisting of natural lithium are sensitive to slow neutrons, their response to neutrons being enhanced by 6Li-enriched lithium or suppressed by using lithium consisting entirely of 7Li. Pairs of 6LiF/7LiF detectors allow distinguishing between neutron/non-neutron components of a radiation field. For detection of neutrons of higher energy, polyethylene (PE-300) moderators were used. TLDs, located in the centre of cylindrical moderators, were installed at eleven positions in the JET hall and the hall labyrinth in July 2012, and exposure took place during the last two weeks of the experimental campaign. Measurements of the gamma dose were obtained for all positions over a range of about five orders of magnitude variation. As the TLDs were also calibrated in a thermal neutron field, the neutron fluence at the experimental position could be derived. The experimental results are compared with calculations using the MCNP code. The results confirm that the TLD technology can be usefully applied to measurements of neutron streaming through JET Torus Hall ducts. 相似文献
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J. Kotakoski A.V. Krasheninnikov K. Nordlund 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,240(4):810-818
We have studied the low energy irradiation of carbon nanotubes (CNT) with K ions using classical molecular dynamics simulations with analytical potentials. The studied CNTs had diameters of about 0.5–1.2 nm and single or multiple walls. The average penetration depth and probabilities to introduce an impurity atom into CNT were studied with simulations on irradiating the CNT with single K ion. The number of potassium clusters, their average sizes and the damage produced into the CNT due to the irradiation were studied using multiple K ion irradiations. We found that the K ions are mobile in CNTs right after the implantation event and that they cluster together. For CNTs with 1–3 coaxial tubes, the highest ratio of K atoms in clusters per total number of K ions was obtained by using an irradiation energy of about 100 eV. Also the least damage per K ion was found to be produced into the CNT with this energy when those energies high enough for the ion to penetrate the outermost wall of the CNT were considered. 相似文献
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ZHANG Lei 《等离子体科学和技术》2015,17(11):958-963
In this work, a time-of-flight (TOF) mass spectrometer has been used to investigate the distribution of intermediate species and formation process of carbon clusters. The graphite sample was ablated by Nd:YAG laser (532 nm and 1064 nm). The results indicate that the maximum size distribution shifted towards small cluster ions as the laser fluence increased, which happened because of the fragmentation of larger clusters in the hot plume. The temporal evolution of ions was measured by varying the delay time of the ion extraction pulse with respect to the laser irradiation, which was used to provide distribution information of the species in the ablated plasma plume. When the laser fluence decreased, the yield of all of the clusters obviously dropped. 相似文献
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Hideaki Yamada Kazuya Ichiki Yoshihiko Nakata Satoshi Ninomiya Toshio Seki Takaaki Aoki Jiro Matsuo 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(11-12):1736-1740
Molecular imaging of animal cells was successfully obtained by using the technique of MeV-energy probe secondary ion mass spectrometry (MeV-SIMS) and sample etching with Ar cluster ion beam. In order to indicate benefits of using Ar cluster beam for etching biomaterials, cholesterol and phospholipids were etched with Ar cluster ions and SIMS measurements for the before and after etching samples were performed. Moreover, secondary ion images of the animal cells etched with Ar cluster ions were acquired by using MeV-energy ion beam as a probe. 相似文献
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Talayeh Rezayat 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,264(2):400-403
Kinetic energy distributions of fragment ions from hyperthermal energy collisions of ions with a self-assembled monolayer surface of fluorinated alkyl thiol on gold substrate and a LiF surface (vapor deposited on titanium substrate) have been measured as a function of scattering angle and fragment ion mass. These distributions for the thiol surface show two energetically and angularly distinct pathways for the dissociation of ions while those from LiF show only one peak. A plot of the velocities of the fragment ions as a Newton diagram for these two processes clearly demonstrates that one process is due to the collision of ions with a fraction of the molecular chain of the monolayer surface molecule with scattering over a broader angular range while the other process is due to collision of the projectile ions with the monolayer surface acting as a bulk surface with fragment ions scattering close to the surface parallel and resembles the Newton diagram from the LiF surface. 相似文献
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T. Muramoto M. Okai Y. Yamashita K. Yorizane Y. Yamamura 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2001,180(1-4):222-229
The cluster ejection due to cluster impact on a solid surface is studied through molecular dynamics (MD) simulations. Simulations are performed for Cu cluster impacts on the Cu(1 1 1) surface for cluster energy 100 eV/atom, and for clusters of 6, 13, 28 and 55 atoms. Interatomic interactions are described by the AMLJ–EAM potential. The vibration energy spectrum is independent of the incident cluster size and energy. This comes from the fact that sputtered clusters become stable through the successive fragmentation of nascent large sputtered clusters. The vibration energy spectra for large sputtered clusters have a peak, whose energy corresponds to the melting temperature of Cu. The exponent of the power-law fit of the abundance distribution and the total sputtering yield for the cluster impacts are higher than that for the monatomic ion impacts with the same total energy, where the exponent δ is given by Yn∝nδ and Yn is the yield of sputtered n-atom cluster. The exponent δ follows a unified function of the total sputtering yield, which is a monotonic increase function, and it is nearly equal to δ −3 for larger yield. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(10):1060-1064
To explore local structures around lithium ions and to estimate lithium isotopic reduced partition function ratios (RPFRs) ofsolvated lithium ions in ethylene carbonate (EC), methylethyl carbonate (MEC) and EC/MEC mixed solvent systems, ab initio molecular orbital calculations at the HF/6-31G(d) level of theory were carried out. Both EC and MEC were coordinated to lithium ions using their carboxyl oxygens and the Li-O bond distance increase with increasing solvation number up to 4 in the primary solvation sphere both in EC and MEC systems. Binding energy calculations suggested that EC was preferentially coordinated to the lithium ion in the EC/MEC mixed solvent system. RPFRs of solvated lithium ions were convex functions of the solvation number between 1 and 4 and took the maxima at 3 both in EC and MEC systems. The RPFR value in EC/MEC mixed solvent system was estimated to be 1.07818 at 25°C. 相似文献