高能氩离子在聚苯乙烯中的电子能损效应研究

用1.4GeV氢离子对多层堆叠的厚约53m的聚苯乙烯薄膜在室温和真空条件下进行了辐照;对辐照后的样品进行了从红外到紫外的光吸收测量.测量结果显示,材料经高能红离子辐照后发生化学降解,降解过程强烈依赖于电子能损;在能量沉积密度很高的径迹芯中,分子主链和苯环均遭到破坏;在电子能损高于0.77keV/nm时有炔基产生.     

高能氩离子辐照硅产生的缺陷研究

在室温下750MeV氩离子对本征单晶硅进行辐照,通过用正电子湮没寿命测量技术、电子顺磁共振技术以及红外光吸收方法研究了辐照产生的缺陷.结果表明:电中性双空位是辐照产生的主要空位团;在4.3×10¹⁴ions/cm²的高剂量下未见样品发生非晶化转变;虽然在离子射程末端双空位的浓度随剂量的增加而显著增大,但在以电离激发过程为主要能损方式的区域里双空位的浓度基本不变.据此可以认为,电子能损过程对辐照产生的缺陷有退人作用.     

高压条件下高能重离子辐照材料研究进展

高能重离子辐照处于高压条件下材料的研究,是随着高能重离子加速器技术的快速发展而出现的一个新的研究领域, 研究结果涉及材料学、 地质学、地质年代学、核废料处理学等学科。简要介绍最近几年国内外在高能重离子辐照高压条件下材料研究领域的研究现状及已取得的结果,并对未来在兰州重离子加速器冷却储存环（HIRFL CSR）上开展相关研究工作的前景作了展望。With development of high energy heavy ion accelerator, it is possible to perform heavy ion irradiation experiments of pressurized materials in diamond anvil cells(DACs). It is a new research field. The results expected from irradiation experiments under high pressure will have impacts on several scientific fields such as materials science,geo science,geochronology,and nuclear waste storage. In this paper, some of recent works in this field are presented and reviewed. Furthermore,the research plan of materials under high pressure based on HIRFL-CSR is introduced.     

Aligned Elongation of Ag Nanoparticles Embedded in Silica Irradiated with High Energy Ni Ions

Metallic nanoparticle(NP) shapes have a significant influence on the property of composite embedded with metallic NPs. Swift heavy ion irradiation is an effective way to modify shapes of metallic NPs embedded in an amorphous matrix. We investigate the shape deformation of AgNPs with irradiation fluence, and 357 MeV Ni ions are used to irradiate the silica containing AgNPs, which are prepared by ion implantation and vacuum annealing. The UV-vis results show that the surface plasmon resonance(SPR) peak from AgNPs shifts from 400 to 377 nm. The SPR peak has a significant shift at fluence lower than 1 × 10~(14) ions/cm2 and shows less shift at fluence higher than 1 × 10~(14) ions/cm~2. The TEM results reveal that the shapes of AgNPs also show significant deformation at fluence lower than 1 × 10~(14) ions/cm~2 and show less deformation at fluence higher than1 × 10~(14) ions/cm~2. The blue shift of the SPR peak is considered to be the consequence of defect production and AgNP shape deformation. Based on the thermal spike model calculation, the temperature of the silica surrounding Ag particles first increases rapidly, then the region of AgNPs close to the interface of Ag/silica is gradually heated. Therefore, the driven force of AgNPs deformation is considered as the volume expansion of the first heated silica layer surrounding AgNPs.     

纯金属中电子能损效应的实验研究

简要评述了快重离子辐照在纯金属中引起的电子能损效应的实验研究结果 ,特别是强电子能损在金属中引起的辐照缺陷的部分退火、新缺陷的产生 .离子潜径迹的形成和辐照相变等. As swift heavy ions are available for irradiation damage study, it has been tried to evidence whether electronic energy loss might play a role in the damage processes of metallic targets. Experimental investigations showed that, as increase of electronic energy loss, large amount of electronic energy loss can result in radiation annealing of part of defects produced by elastic collisions, defect creation, latent track formation, as well as phase transition, and so on. Pure metals...     

重离子生物分子作用中的电子能损

对重离子与生物分子相互作用中能量损失的物理机制进行了分析和讨论, 对现有电子能量损失的研究进展进行了评述, 指出将要研究的方向。     

MeV能量离子在生物样品中的能量损失与能量离散

为了研究 MeV能量离子在生物样品中的能量损失与能量离散, 分别使用1.0, 1.8和2.8 MeV质子和4.5 MeV氦离子分别辐照不同质量厚度的洋葱内表皮膜。 当质子穿过该生物样品后, 可以利用透射能谱测量透射离子的能量损失和能量离散。 实验结果显示, 在以上的生物样品中, MeV能量离子的能量损失值和TRIM程序模拟的结果相吻合, 但是透射离子的能量离散值却与TRIM程序模拟结果有很大的不同。 结合生物样品的结构不均匀的特性, 对Bohr能量离散理论进行了修正, 并发现修正后的Bohr能量离散理论计算结果与实验值符合得很好。     

MeV能量离子辐照拟南芥干种子和含水种子存活曲线对比

离子束辐照植物种子所产生的水自由基对植物种子存活率会有影响, 实验中为了观察这种辐射效应, 采用6.5 MeV能量的质子分别辐照拟南芥干种子和含水种子。 这个能量点的质子无论对干种子还是含水种子都可以完全穿透, 减少了因损伤部位不同带来的差异。 实验中采用的质子注量从4×109 ions/cm2到1×1014 ions/cm2。 实验结果显示干种子和含水种子存活曲线均成肩形下降趋势,而且含水种子下降注量点明显低于干种子。 这是自由基作用结果。 同时在辐射生物学靶学说的基础上, 建立了模型, 通过参数的合理设置,很好地拟合了实验数据。 The dry and water saturated seeds of Arabidopsis thaliana were irradiated by H+ions with 6.5 MeV in atmosphere. The ion fluence used in this experiment was in the range of 4×109 —1×1014 ions/cm2. According to the structure of the seed and TRIM simulation, the ions with the energy of 6.5 MeV can penetrate the whole seed. The experiment shows that the fluence response curves for the dry seeds and water saturated seeds had distinct shoulders and reduced rapidly. The experimental results show that the water imbibed seeds were more sensitive than the dry seeds and the reason is from free radicals reaction. A model has been constructed, and primely simulates the experiment data.     

Electronic Energy Loss and Straggling of Protons in Metals

By making use of the linear-response dielectric theory and local electron density approximation, we calculate the electronic stopping cross section and energy straggling. of protons in metals. The correlation and exchange interaction of electron gas in metals is taken into consideration by introducing a local-field-correction function.in the dielectric function. The theoretical results are compared with experimental and empirical data, as well as with other previous theoretical results.     

Optical and Structural Modifications in Heavy Ion Irradiated Polystyrene

Samples of polystyrene (PS) have been irradiated with ⁶⁴Cu (50 and 120 MeV) and ¹²C (70 MeV) ion beams (fluence=10¹¹ to 10¹³ ions cm^?2) in order to study the induced modifications using UV‐VIS and FTIR spectroscopy. UV spectra of irradiated samples reveal that the optical band gap decreases from 4.36 to 1.46 eV in PS. The decrease in optical band gap is more pronounced with the Cu‐ion beam due to high electronic energy loss as compared to the C ion beam. The effect of low energy (50 MeV) Cu ions on the optical properties of PS is larger than that due to high energy (120 MeV) Cu ions. The correlation between the optical band gap and the number of six member carbon rings inside the largest carbon clusters embedded in the network of polystyrene is discussed. FTIR spectra reveal the formation of hydroxyl, alkene, and alkyne groups in the Cu‐ion irradiated PS. Changes in the intensity of the absorption bands on irradiation with C‐ion relative to pristine samples have also been observed and are discussed.     

入射粒子与靶相互作用中电子能损的高阶修正

研究了在较高能入射离子（He离子、 12_C离子）与靶相互作用中电子能量损失的物理机制, 分别探讨了电子能量损失中的相对论修正、 壳修正、 密度修正以及Barkas效应和Bloch效应等修正的贡献, 发现壳修正、 Barkas效应修正和Bloch效应修正在能量小于100 MeV时是重要的, 而相对论修正和密度修正是在能量大于100 MeV时起作用。 加入各种修正项之后, 电子阻止本领的计算结果和实验值（ICRU49）符合更好。 The mechanisms of electronic energy loss in the process of incident particles interaction with Si and Al₂O₃ at proper energies are investigated. The contribution to the electronic energy loss from high order corrections, such as the relativistic correction, the shell correction, the density correction, the Barkas effect correction and the Bloch effect correction are discussed respectively. It is found that the shell correction, the Barkas effect correction and the Bloch effect correction are important at low energies, the relativistic correction and the density correction are important at high energies. The calculated results with these higher order corrections are in good agreement with the experiment data (ICRU49).     

团簇离子在固体中能损的非线性效应

研究了每核子能量为 2 6 0— 4 5 0keV的H₊2,H₊3,H₊4 H₊5和H₊7团簇离子在金膜中的能损 .发现团簇离子中平均每个质子的能损大于相同速度的单质子能损 ,即能损比大于 1,且随团簇离子的大小和速度的增加而增加. The energy losses of cluster ions H₊2,H₊3,H₊4 H₊5 and H₊7with energy of 260-450 keV/p in solid films have been measured. It has been found that the energy loss per proton in clusters is larger than that of single proton with the same velocity as clusters, that is, the energy ratio is larger than 1. Energy ratio increases with increasing the cluster size and velocity.     

Effects of Ions Charge-Mass Ratio on Energy and Energy Spread of Accelerated Ions in Laser Driven Plasma

Effects of ions charge-mass ratio on energy and energy spread of accelerated ions in laser driven plasma are investigated in detail by proposing a simple double-layer model for a foil target driven by an ultrastrong laser. The radiation pressure acceleration mechanism plays an important role on the studied problem. For the ions near the plasma mirror, i.e. electrons layer, the dependence of ions energy on their charge-mass ratio is derived theoretically. It is found that the larger the charge-mass ratio is, the higher the accelerated ions energy gets. For those ions far away from the layer, the dependence of energy and energy spread on ions charge-mass ratio are also obtained by numerical performance. It exhibits that, as ions charge-mass ratio increases, not only the accelerated ions energy but also the energy spread will become large.     

MeV能量的重离子辐照GaN的HRXRD研究

分别进行了2.3 MeV20 Ne8+ 离子和5.0 MeV84 Kr19+ 离子辐照GaN样品的实验, 并对实验样品进行了HRXRD的分析。结果发现, 随着这两种离子辐照剂量的增大, GaN的HRXRD谱（0002）衍射峰的峰位出现了向小角侧有规律的移动, 并在较高剂量时衍射峰发生分裂。同时, 对衍射峰的峰位的移动和峰形的变化等现象反映的辐照损伤机制进行了研究, 并探讨了电子能损与核能损各自在晶格损伤中的作用。Irradiation experiments of gallium nitride (GaN) with 2.3 MeV20 Ne8+ and 5.0 MeV84 Kr19+ respectively were performed. The irradiated samples were analyzed using the high\|resolution X\|ray diffraction (HRXRD) spectrometry. It was found that the diffraction peak of GaN (0001) exhibited regular shift to smaller diffraction angles with the increase of ion fluence for the both ions, and the diffraction peak split into a few sub\|peaks at higher irradiation dose. Underlying mechanisms of the observed peak shift and split were investigated, the contributions of different energy losses to the damage accumulation in the irradiated GaN were discussed.     

高能238U离子辐照AlN 晶体薄膜的光学特性研究

通过傅里叶变换红外光谱、拉曼光谱和光致发光谱测试手段分析了由HIRFL 提供的高能238U离子辐照AlN 晶体薄膜的光学特性变化。辐照后出现了A1(To),A1(Lo),E1(To) 和E2 等声子振动吸收模式,并且辐照使其在样品近表面Al—N 等振动模式遭到破坏后悬空的Al— 键很快与空气中的O离子发生结合,形成了Al—O 键。综合分析得出了蓝光发射带是与O 离子相关的VAl-ON-3N 和VAl-2ON-2N两种类型缺陷以及F-型缺陷聚合所致;绿光发射带是由基底中Al 原子产生的价带之间的跃迁所致。AlN thin film irradiated with 100 MeV 238U ions delivered from HIRFL (Heavy Ion Research Facility in Lanzhou) were investigated by Fourier Transform Infrared spectra, Raman spectra and Photoluminescence spectra. Phonon vibration absorption modes including A1(To), A1(Lo), E1(To) and E2 appeared in the irradiated samples. The irradiation made the Al—N bonds broken and the formation of Al—dangling bonds, which combined soon with oxygen atoms existing in air to form Al—O bonds. Blue light emission band are related to the two types of defects of VAl-ON-3N and VAl-2ON-2N and F-type defects aggregation. Green light emission band is due to energy transition among valence band of Al atoms in sapphire substrate.     

飞秒强激光作用下Ar原子团簇离子能谱计算

研究了飞秒强激光与Ar原子团簇相互作用时的电离机制及库仑爆炸过程,建立了一个简化的模型计算相互作用产生的离子能谱,计算结果与实验结果较为吻合,可以较好地解释离子能谱高能端的主要特征。     

高能p-A碰撞的碰撞几何、能量损失和横能分布

采用一种仔细考虑了作用截面、表面弥散和形变效应的核碰撞几何,同时考虑到在每一次碰撞中领头质子损失能量,得到了高能ｐ－Ａｌ碰撞的横能分布,计算结果与２００ＧｅＶ／ｃｐ－Ａｌ、Ｃｕ及Ｕ碰撞的实验数据符合.In this paper, the nuclear collision geometry which was considered carefully in the interaction cross sections, surface effects and nuclear deformations is adopted. The energy loss of leading proton in each collision is considered. The transverse energy distributions in high energy p A collisions are obtained. The calculated results are in agreement with the experiment data of 200 GeV/ c p Al, Cu and U collisions.     

Molecular-Dynamics Simulation of the Interaction of Argon Cluster Ions with Titanium Surface

The molecular-dynamics simulation of impacts of accelerated argon cluster ions with titanium surface is carried out. The dependences of the dimensions of the produced defects and of the number of sputtered titanium atoms on the cluster-ion dimensions, energies, and incidence angles are studied.