645 MeV Xe35+离子辐照SiO2在线光发射的研究

离子辐照可以改变二氧化硅(SiO₂)的晶体结构和光学性质.采用645 MeV Xe³⁵⁺离子辐照SiO₂单晶,在辐照过程中,利用光栅光谱仪测量在200—800 nm范围内的光发射.在发射光谱中,观测到中心位于461和631 nm的发射带.这些发射带是弗伦克尔激子辐射退激产生的,其强度与辐照离子能量和辐照离子剂量密切相关.实验结果表明:发射光强随离子在固体中的电子能损呈指数增加.由于离子辐照对晶体造成损伤,发射光谱强度随辐照剂量的增加而降低.文中讨论了这些与晶体结构有关的发射带,结合能量损失机制讨论了激子形成和退激过程.快重离子辐照过程中发射光谱的原位测量对研究辐照改性具有重要意义,有助于揭示离子辐照引起晶体损伤的物理机制.     

荷能离子在C60薄膜中引起的辐照效应

用 Raman散射和 XPS技术分析了能量为几百 ke V到几百 Me V的多种离子在 C60 薄膜中引起的辐照效应.分析结果表明 ,在低能重离子辐照的 C60 薄膜中 ,其晶态向非晶态的转变过程是由核碰撞主导的.在快离子 (1 2 0 ke V的 H离子和171.2 Me V的 S离子 )辐照的情况下,电子能损起主导作用.发现在H离子辐照过程中,电子能损有明显的退火效应 ,致使 C60 由晶态向非晶态转变的过程中,经历了一个石墨化的中间过程;而在 S离子辐照的情况下 ,电子能损的破坏作用超过了退火效应 ,因此 ,在C₆₀ 由晶态向非晶态转变的过程中,无石墨化的中间过程.Irradiation effecs (mainly including transformation from crystalline into amorphous state) of C 60 films induced by 120 keV H, He, N, Ar, Fe and Mo ions, 240 keV and 360 keV Ar ions, and 171.2 MeV, 125.3 MeV and 75.8 MeV S ions were analysed by means of Raman scattering and XPS technique. The analysis results indicate that amorphization process in the cases of N, Ar, Fe and Mo ions irradiation is dominated by nuclear collision, but in the case of H ion irradiation, the process is...     

快重离子辐照聚酰亚胺潜径迹的电子能损效应

快重离子辐照聚合物材料时，由于密集电离激发在其路径上产生几纳米直径的潜径迹，径迹形貌受离子种类、离子能量等多种因素的影响.为了研究电子能损对径迹形成所起的作用，利用1.158GeV 的Fe⁵⁶离子和 1.755GeV Xe¹³⁶离子在室温真空环境下辐照叠层聚酰亚胺(PI)薄膜，结合傅里叶转换红外光谱(FTIR)分析技术对辐照引起的化学变化进行了测量.聚酰亚胺官能团的降解及炔基的生成是离子辐照聚合物的主要特征，在注量1×10¹¹到6×10¹²/cm²范围及较宽的电子能损(dE/dX)_e范围 (Fe⁵⁶ 离子：2.2 到 5.2 keV/nm， Xe¹³⁶ 离子：8.6 到 11.3 keV/nm)对官能团的断键率及炔基生成率进行了研究. 红外结果显示在实验涉及的能损范围都有炔基生成，应用径迹饱和模型对实验结果进行拟合，不同能损下的平均损伤径迹半径及炔基生成径迹半径被得到，通过热峰模型对实验结果拟合，给出了离子在聚酰亚胺中产生潜径迹的能损阈值，实验给出的径迹形貌的电子能损效应曲线与热峰模型预言走势基本一致. 关键词： 离子辐照 潜径迹 红外光谱 热峰模型     

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.     

近玻尔速度Ne2+离子穿过碳膜引起的电子发射

本文测量了入射能为2–25 keV/u的Ne²⁺离子穿过不同厚度碳膜诱导的前向、后向 (分别对应出射表面和入射表面) 电子发射产额. 实验中通过改变炮弹离子的能量, 系统的研究了势能沉积、电子能损以及反冲原子对前向、后向电子发射产额的贡献. 结果表明, 离子的势能沉积只对后向电子发射有贡献, 前向、后向电子发射产额分别与Ne²⁺离子在薄膜出射、入射表面的电子能损近似成正比关系, 其中电子能损很低 (对应于离子能量很低) 的时候, 反冲原子对电子发射的贡献不能忽略. 关键词： 近玻尔速度 电子发射 电子能损 反冲原子     

不同离子辐照氟化锂材料时原位发光光谱测量分析

在BNU400注入机上搭建的离子激发发光(ion beam induced luminescence,IBIL)测量装置上,开展了相同能量(100 keV)条件下的3种离子(H~+、He~+以及O~+)辐照氟化锂材料时的IBIL光谱的原位测量工作,对比研究离子种类对氟化锂材料辐照缺陷的生成及其演变行为的影响.结合SRIM(Stopping and Range of Ions in Matter)模拟的结果,可以发现He~+辐照时的IBIL光谱强度最高,这是由于He~+激发产生的电子空穴对密度高于H~+,而O~+辐照时由于激发出的电子空穴对密度过高引起的非辐射复合比例增加,从而导致发光效率过低;质量数越大的离子辐照时,核阻止本领越大,会加快缺陷的生成和湮灭速率,降低达到平衡状态时的发光强度.近红外波段的F_3~-/F_2~+色心发光峰强度及其演变行为表明其耐辐照性能好于可见光波段的F_2色心.     

25 MeV/u Kr辐照下PET薄膜的损伤机制研究

通过25 MeV/u 86 Kr离子辐照叠层结晶聚对苯二甲酸乙二醇酯膜（PET）, 在不同的电子能损（3.40-7.25 keV/nm）和离子注量(5×1011----3×1012 ions/cm2)辐照条件下, 对Kr离子在PET中引起的辐照损伤效应进行了研究。借助傅里叶变换红外光谱分析,通过对样品的红外吸收峰进行扣除基底后的Lorentz拟合,分析了与主要官能团对应的吸收峰强度的变化趋势, 研究了化学结构与组分在重离子辐照下的变化规律; 利用X射线衍射光谱仪测量, 研究了Kr离子在PET潜径迹中引起的非晶化过程,并通过对吸光度和非晶化强度随离子注量的指数衰减规律的分析, 获得了不同电子能损离子辐照PET时主要官能团的损伤截面和非晶化截面及对应的潜径迹半径。 At room temperature, polyethylene terephthalate(PET) foil stacks were irradiated by 25 MeV/u Kr ions in the electronic stopping power range(3.3--7.66 keV/nm) and the fluence range from 5×1011 to 3×1012 ions/cm2. The behaviour of the main function groups with fluence and electronic stopping power were studied by using Fourier transform infrared(FTIR) spectroscopy, the degradation of the function group was investigated with the Lorentz fitting subtracted baseline. The amorphous processes in the latent tracks of PET were studied by X ray diffraction(XRD) measurements. The Kr ion induced degradation cross section and amorphisation cross sections(radii) for different electronic energy loss were acquired from the experimental data(FT IR and XRD) by exponential decay function respectively.      

热峰模型在聚碳酸酯非晶化潜径迹中的应用

为了描述快重离子在聚合物中的潜径迹行为，用不同能量的快重离子 (1158GeVFe5656,1755GeVXe136¹³⁶及2636GeVU238²³⁸) 辐照 叠层半结晶聚碳酸酯膜 (Makrofol KG型)，结合x射线衍射测量技术，在较宽的电子能损 (1 9—171keV/nm)和离子注量（5×1010¹⁰—3×1012¹² cm-2^-2）范围研究了离子在半 关键词： 离子辐照 聚碳酸酯 非晶化 潜径迹     

O~(2+)离子穿过碳膜引起的前后表面电子发射

测量了入射能为1.9~11.3 keV/u的O~(2+)离子穿过碳膜诱导的前向、后向(分别对应出射表面和入射表面)电子发射产额。实验中,通过改变入射离子的能量和流强,系统地研究了电子能损和离子束流强度对前向、后向电子发射产额的影响。结果表明,在本实验的能量范围内,前向、后向电子发射产额与对应表面的电子能损有近似的正比关系,而与束流强度无关。分析还发现引起后向电子发射的动能阈值约为0.2 keV/u,势能电子发射产额约为1 e~-/ion。     

反冲原子对低速离子轰击Si表面时电子发射产额的影响

在兰州重离子加速器国家实验室电子回旋共振离子源高电荷态原子物理实验平台上,用低能(0.75keV/u≤EP/MP≤10.5keV/u,即3.8×105m/s≤vP≤1.42×106m/s)He2+,O2+和Ne2+离子束正入射到自清洁Si表面时二次电子发射产额的实验结果.结果表明电子发射产额γ近似正比于入射离子动能EP/MP.在相同动能下,γ(O)γ(Ne)γ(He),对于原子序数ZP比较大的O2+和Ne2+离子,ZP大者反而γ小,这与较高入射能量时的结果截然不同.通过计算不同入射能量下入射离子的阻止能损S,发现反冲原子对激发二次电子的作用随入射离子能量的降低显著增大,这正是导致在较低能量范围内二次电子发射产额与较高入射能量时存在差异的主要原因.     

High energy heavy ion tracks in bubble detectors

Bubble detectors which are commonly used as neutron detectors have been demonstrated through this study to be good detectors for registration of high energy heavy ion tracks. Large size bubble detectors made in China Institute of Atomic Energy were irradiated to heavy ions Ar and C up to 650 MeV/u and 400 MeV/u, respectively. Very clear features of stringy tracks of high energy heavy ions and their fragmentations are manifested and distinguishable. A single track created by a specific high energy heavy ion is composed of a line of bubbles, which is visible by naked eyes and retained for months wihhout reduction in size. The creation of heavy ion tracks in bubble detectors is governed by a threshold whose essence is approximately a critical value of energy loss rate (dE/dX)_c similar to that of etch track detectors. Ranges of heavy ions in bubble detectors are apparent and predictable by existing formulas. Identification of high energy heavy ions and the applications to heavy ion physics, cosmic rays, exotic particles and cancer therapy monitoring are obviously promising. The experimental and theoretical aspects of high energy heavy ion tracks in bubble detectors as well as the expectable applications are presented and discussed.     

Latent track creation in fused silica by 200 MeV silver beam

Studies of formation of latent tracks in swift heavy ion irradiated SiO₂ are presented. Fused silica (SiO₂) were irradiated with 200 MeV silver (Ag) ion beam at varying fluences. Radiation-induced effects were studied by ultraviolet(UV)/Visible optical absorption spectroscopy and transmission electron microscopy (TEM). UV/Visible absorption study indicated E′ centers and oxygen deficiency centers having characteristic absorption occurred at 5 eV. The density of these color centers calculated from the absorption peak intensity showed Poisson-type variation with irradiation fluence. The defects are thus entirely confined to the latent tracks created by swift heavy ions in SiO₂. The track radius estimated from optical absorption study was found to be 5.1 nm. Similar results were obtained from TEM studies of the irradiated samples.     

载能团簇离子在物质中的能量损失

实验表明,团簇离子在物质中的能量损失并不等于各成分单独作用的总和,而是具有非线性效应．这种非线性效应与团簇离子的能量、团簇的种类和大小、团簇成分之间的空间关联程度以及作用物质的结构有关．对团簇作用的非线性效应研究对于了解团簇与物质相互作用的机制具有非常重要的理论意义．MeV能区的团簇离子在物质中的非线性电子能损和核能损方面的直接实验数据还相当缺乏,其理论模型也更待建立．评述了载能团簇离子在物质中的能量损失及测量方法．Fast ions deposit energy in matter through electronic and nuclear collision processes. The relaxation of the deposited energy induces emission of photons, electrons, ions, and neutral species from the target. Comparing with single incident ion, cluster induces many new phenomena: such as non-linear energy loss, non-linear emission of secondary ions, production of giant tracks and craters in various irradiated materials. These new phenomena induced by clusters are attributed to the vicinage effect ......     

喷气式Z箍缩等离子体装置中离子束能谱的测量

利用新研制的紧凑型汤姆生离子能谱仪（ＴｈｏｍｓｏｎＩｏｎＥｎｅｒｇｙＡｎａｌｙｚｅｒ），对喷气式Ｚ－箍缩等离子体装置中离子能谱进行了测量，在ＣＲ－３９上得到了清晰的Ａｒ＋，Ａｒ２＋，Ａｒ３＋离子抛物线轨迹，通过分析计算结果表明：离子的最大能量在１ＭｅＶ左右，离子能谱分布曲线都随其能量增加而单调下降。     

利用重离子辐照技术制备锂离子电池隔膜

用能量11.4MeV/u和注量1×108ions/cm2的197Au离子垂直辐照聚丙烯薄膜,通过电导测量法监测温度、硫酸浓度和重铬酸钾浓度对径迹蚀刻速率的影响,得到合适的蚀刻条件;成功制备出孔径范围在600—1000nm的重离子径迹聚丙烯孔膜,并用场发射扫描电镜对孔的形状及孔径大小进行了表征,对孔洞锥角的形成进行了分析,为重离子辐照技术制备锂离子电池隔膜提供了实验数据。     

Probing charge carrier compensation in high energy ion irradiated III–V semiconductor by Raman spectroscopy and Hall measurements

Raman spectroscopy and Hall measurements have been carried out to investigate the differences in near‐surface charge carrier modulation in high energy (~100 MeV) silicon ion (Si⁸⁺) and oxygen ion (O⁷⁺) irradiated n‐GaAs. In the case of O ion irradiation, the observed decrease in carrier concentration with increase in ion fluence could be explained in the view of charge compensation by possible point defect trap centers, which can form because of elastic collisions of high energy ions with the target nuclei. In Si irradiated n‐GaAs one would expect the carrier compensation to occur at a fluence of 2.5 × 10¹³ ions/cm², if the same mechanism of acceptor state formation, as in case of O irradiation, is considered. However, we observe the charge compensation in this system at a fluence of 5 × 10¹² ions/cm². We discuss the role of the complex defect states, which are formed because of the interaction of the primary point defects, in determining carrier concentration in a Si irradiated n‐GaAs wafer. The above results are combined with the reported data from the literature for high energy silver ion irradiated n‐GaAs, in order to illustrate the effect of both electronic and nuclear energy loss on trap creation and charge compensation. Copyright © 2016 John Wiley & Sons, Ltd.     

Modification of the Al<Subscript>2</Subscript>O<Subscript>3</Subscript> surface by high-energy bismuth ions

This paper reports on an atomic-force microscopy study of the surface of α-Al₂O₃ single crystals irradiated by Bi ions with energies of 710, 557, 269, and 151 MeV. The shape of the radiation defects produced by single ions was established to depend on the ionization energy loss. The threshold ionization density above which the surface topography is observed to change lies in the 27–35 keV/nm interval. Possible mechanisms of defect formation in the thermal-spike model, namely, a phase transition and the creation of thermoelastic stresses in the high-energy ion track, are considered.     

Ionizing particles may create shockwaves

To find a model that describes the gas diffusion on irradiated polymers (Makrofol KG polycarbonate) the diffusion constants have been measured with argon as diffusion gas. The polymers were irradiated with uranium, gold and lead ions of about 10 MeV/u and ion fluences between 1×10¹⁰ and 4×10¹¹ ions/cm². The ion irradiated probes show two quite different dependencies of the diffusion constant on the ion energy loss. These effects are strongly related to the fluence of the irradiation. In case of low ion fluences, the diffusion constant is up to 8 times higher than that of pristine material. In the probes with high ion fluences we observe a decrease of diffusion constant to half the value of the pristine material. To understand the dependence of the diffusion constant on ion fluences we apply a model of compacting. This model describes the compacting ability of shockwaves arising from latent tracks. A track formation model is suggested. When an ion penetrates the foil it creates shockwaves around its path. These shockwaves put compacting forces on earlier created latent tracks in the same foil.     

UV–blue photoluminescence from ZrO2 nanopowders prepared via glycine nitrate process

This work is motivated by heavy-ion irradiation of materials exposed to high hydrostatic pressures in a diamond anvil cell (DAC). Those studies require the complete passage of ions through one of the two anvils consisting of natural diamond. Due to typical anvil lengths of about 2–3 mm, ion energies of a few hundred MeV/u, as provided by the SIS heavy-ion synchrotron of GSI, are needed. Data of energy loss and range of ions in this energy regime being scarce for diamond, a set of experiments was devoted to range measurements by irradiating a single DAC diamond and an immediately following stack of 100 polycarbonate foils (each 30-m thick) with ²³⁸U ions of 50.3 GeV (211.5 MeV/u). Ion range and range straggling in the stack were determined by etching the tracks and counting the pores. The experimentally determined ion range in the polymer foil stack is consistent with energy-loss values in diamond and polymer obtained with the SRIM and ATIMA computer codes and also confirms the reliability of these codes for diamond. Therefore, SRIM and ATIMA will be used in further experiments aimed at heavy-ion irradiation of materials pressurized in DACs. PACS 07.35.+k; 61.80.Jh; 61.85.+p; 81.05.Uw     

The Localized Pinch Model as a High Energy Ion Collective Acceleration Mechanism

We present analytic and numerical calculations of the localized pinch model for ion collective acceleration by intense relativistic electron beams. These studies demonstrate the model's postulated synchronous acceleration of the ion clump and beam pinch. However, the configuration is found to be phase unstable, terminating the acceleration process before significant ion energy is acheived. Therefore, although the localized pinch model may be an appropriate explanation for some previous experimental observations of collectively accelerated MeV ions, it does not appear to be a suitable mechanism for high energy ion acceleration.