氘团簇离子(d3+)固体与相互作用过程中的团簇行为研究

讨论了由三个氘原子组成的氘团簇离子(d3+)束与独立氘离子束在轰击固体靶时,在原子过程和D-D核聚变过程中体现出的差别.对氘团簇与固体靶相互作用的机理进行了分析.     

氘团簇离子(d3+)固体与相互作用过程中的团簇行为研究

讨论了由三个氘原子组成的氘团簇离子(d     

碳团簇C_n~+(n=1─5)注入NaCl晶体的模型

600keV的荷能碳团族离子C+n（n=1─5）注入到NaCl单晶,当入射粒子的速度v大于玻尔速度v0（=c/137）时,能量转移主要是由入射粒子与靶原子的核外电子碰撞造成的。假定团簇中各原子的能量歧离大于它们的结合能时,团簇状态已经结束,各原子成为独立的粒子。利用Trim程序对碳团簇在NaCl单晶中的射程进行了模拟,得到团簇区域的长度为278－321nm,总射程为686nm。     

碳团簇Cnn+(n=15)注入NaCl晶体的模型

６００ｋｅＶ的荷能碳和簇离子Ｃ＾＋ｎ（ｎ＝１－５）注入到ＮａＣｌ单晶,当入射粒子的速度ｖ大于玻尔速度ｖ０（＝３／１３７）时,能量转移主要是由入射粒子与靶原子的核外电子碰撞造成的。假定团簇中各原子的能量岐离大于它们的结合能时,团簇状态已经结束,各原子成为独立的粒子。     

用串列静电加速器获取MeV高能团簇离子束

利用复旦大学现有的串列静电加速器（ＮＥＣ ９ＳＤＨ－２）获得了能量为１－４ＭｅＶ的硼、碳、硅及金等小型高能团簇离子束：Ｂｎ＾＋（ｎ＝２）、Ｃｎ＾＋（ｎ〈１０）、Ｓｉｎ＾＋（ｎ＝２，３，４）以及Ａｕｎ＾＋（ｎ＝２）；束流强度与团簇的种类和所含的原子数有关，为０．１－１００ｎＡ量级。注入加速器的低能团簇负离子由铯溅射离子源（ＳＮＩＣＳ Ⅱ）产生，高能团簇正离子的质量鉴别用磁分析器完成，高能碳团簇负离子     

低能氘离子束轰击固体靶产生的远程D-D核聚变现象研究

利用强流低能氘离子束轰击由吸氢金属形成的氘自吸收靶，研究固体内Ｄ－Ｄ聚变反应规律。并通过对实验测得的Ｄ－Ｄ聚变伴随粒子能谱，探索Ｄ－Ｄ聚变反应与靶材料结构的相关性。同时，利用氘团簇离子（ｄ＾＋３）氘核（ｄ＾＋）束轰击吸氘固体，研究固体内Ｄ－Ｄ聚变反应的特性。实验中观测到了伴随离子能谱中介于质子峰（３ＭｅＶ）和氚峰（１ＭｅＶ）之间的一个宽峰。结果分析表明，该峰是由固体靶内超出离子射程几倍至十几倍处发     

碳团簇Cn+(n=1-5)注入CR39树脂的吸收光谱研究

利用2×1.7串列加速器产生的团簇离子Cn+(n=l-5)注入到CR39树脂中,树脂的光吸收性质因注入的团簇离子的剂量、剂量率以及团簇中所含原子的个数不同而有不同的变化.该项研究表明团簇与固体相互作用时团簇效应是通过电子阻止来体现的.     

碳团簇及C60负离子的产生

利有铯负离子溅射源和石墨阴极产生并引出了碳团簇负离子流，观察到了一些电子亲和势很小的团簇，用Ｃ６０／Ｃ７０混合物做阴极，也引出了Ｃ６０及其碎片的负离子束，分析了碳团簇负离子束流的质谱组成特点和束流变化的一些规律。     

团簇粒子源及其应用

介绍了蒸发、溅射产生团簇的原理以及通过调节参数得到不同大小的团簇材料，阐述了团簇的基本结构和性质，并介绍了团簇在镀膜及功能膜如光学膜磁性膜方面的应用。     

银纳米团簇复合材料的辐射法制备及性能研究

银纳米团簇作为一种新兴的纳米材料，由于其极小的尺寸，表现出独特的物理化学性能，得到了广泛的关注。本文利用辐射技术设计了一种简单有效的银纳米团簇复合材料的制备方法。利用聚丙烯酸类聚合物分子链携带的羧基，通过辐射还原直接获得了银纳米团簇水溶液。基于辐射接枝技术，将聚丙烯酸模板接枝到不同基体材料上得到固体模板。利用固体模板代替水溶性模板材料，实现了银纳米团簇在固体模板上的原位合成，直接得到银纳米团簇复合材料。制备的银纳米团簇及其复合材料依旧保有银纳米团簇光致发光及催化活性，在金属离子检测和催化4-硝基酚还原加氢具有应用潜力。同时，基体材料的结构与银纳米团簇也会形成协同作用，提高银纳米团簇的使用性能。利用辐射技术简化银纳米团簇复合材料的合成路线，对于不同基体材料具有普适性，扩宽了银纳米团簇复合材料的潜在应用领域。     

荷能团簇束成膜的表面迁移和附着特性的研究

研究了不同能量的团簇碰撞有机物（CH3SiO3/2)衬底形成的表面形貌。结果表明,团簇能量的增大、增加了团簇原子在基片表面的有效碰撞能和迁移力,也改善了沉积薄膜的附着性、致密性、平整性等。特别是有机物上修饰条纹的出现,是迁移力增加的有力证据。     

Study of density effect of large gas cluster impact by molecular dynamics simulations

Large gas cluster impacts cause unique surface modification effects because a large number of target atoms are moved simultaneously due to high-density particle collisions between cluster and surface atoms. Molecular dynamics (MD) simulations of large gas cluster impacts on solid targets were carried out in order to investigate the effect of high-density irradiation with a cluster ion beam from the viewpoint of crater formation and sputtering. An Ar cluster with the size of 2000 was accelerated with 20 keV (10 eV for each constituent atom) and irradiated on a Si(1 0 0) solid target consisting of 2 000 000 atoms. The radius of the Ar cluster was scaled by ranging from 2.3 nm (corresponding to the solid state of Ar) to 9.2 nm (64× lower density than solid state). When the Ar cluster was as dense as solid state, the incident cluster penetrated the target surface and generated crater-like damage. On the other hand, as the cluster radius increased and the irradiation particle density decreased, the depth of crater caused by cluster impact was reduced. MD results also revealed that crater depth was mainly dominated by the horizontal scaling rather than vertical scaling. A high sputtering yield of more than several tens of Si atoms per impact was observed with clusters of 4-20× lower volume density than solid state.     

用于蒙特卡罗并行计算的小型Windows PC集群建设方案

组建了一套针对MCNP5并行计算的小型Windows集群,给出了相关解决方案。以GM计数管对?射线的能量响应相关计算为实例作对比计算的结果表明,用相同经费投入,该集群性能比单CPU计算机要好近5倍,其组建方式快捷,批处理的管理法使集群应用简单灵活。该方法实用、有效,能满足普通用户对计算能力的需求。     

Atomic mobility in energetic cluster deposition

This paper tries to outline the influence of atomic mobility on the initial fabrication of thin films formed by LECBD. Based on our recent studies on low-energy cluster beam deposition (LECBD) by molecular dynamics simulation, two examples, the deposition of small carbon clusters on Si and diamond surfaces and AI clusters on Ni substrate, were mainly discussed. The impact energy of the cluster ranges from 0.1 eV to 100 eV. In the former case,the mobility and the lateral migration of surface atoms, especially the recoil atoms, are enhanced with increasing the impact energy, which promote the film to be smoother and denser. For the latter case, the transverse kinetic energy of cluster atoms, caused mainly by the collision between moving cluster atoms, dominates the lateral spread of cluster atoms on the surface, which is contributive to layer-by-layer growth of thin films. Our result is consistent with the experimental observations that the film structure is strongly dependent on the impact energy. In addition, it elucidates that the atomic mobility takes a leading role in the structure characteristic of films formed by LECBD.     

Vicinage Effects for a Nitrogen Molecular Cluster in Plasmas

The vicinage effects are studied for a fast nitrogen diatomic molecular cluster in a high-density plasma target.A variety of plasma parameters are discussed with regard to stopping power ratio,molecular axis deflection and Coulomb explosion.Emphasis is placed on the vicinage effects on Coulomb explosion and stopping power for a nitrogen cluster in plasmas.The results indicate that vicinage effects influence the correlation between ions in the cluster,and the Coulomb explosion will proceed faster with higher projectile speed,lower plasma density and higher plasma temperature.Comparing hydrogen and nitrogen molecular ions for Coulomb explosion and deflection angle under the same set of parameters,one can find that the nitrogen ion has faster Coulomb explosion and stronger deflection of molecular axis due to the contribution of charge.In the initial stage of the Coulomb explosion the stopping power ratio has a higher value due to enhanced vicinage effects while in the later stage the stopping power ratio approaches one,indicating that the vicinage effects disappear and the ions in the cluster simply behave as independent atomic ions in the plasma.     

Collective excitation of spherical sodium cluster within a semiclassical discription

A microscopic semiclassical Vlasov equation approach is used to investigate the dipole giant resonances of spherical cluster Na14.The main strength distributions of collective response function are located around 2eV region,with a fair agreement with the experiment ones.The results are quite independent of the choice of parameters of the mean field.     

The emission process of secondary ions from solids bombarded with large gas cluster ions

We investigated the effects of size and energy of large incident Ar cluster ions on the secondary ion emission of Si. The secondary ions were measured using a double deflection method and a time-of-flight (TOF) technique. The size of the incident Ar cluster ions was between a few hundreds and several tens of thousands of atoms, and the energy up to 60 keV. Under the incidence of keV energy atomic Ar ions, mainly atomic Si ions were detected, whereas Si cluster ions were rarely observed. On the other hand, under the incidence of large Ar cluster ions, the dominant secondary ions were  (2 ? n ? 11). It has become clear that the yield ratio of secondary Si cluster ions was determined by the velocity of the incident cluster ions, and this strong dependence of the yield ratio on incident velocity should be related to the mechanisms of secondary ion emission under large Ar cluster ion bombardment.     

激光与原子团簇相互作用实验系统的建立

研究建立了激光与原子团簇相互作用的实验系统。该系统包括团簇产生系统、真空系统、激光与团簇同步系统、聚焦系统，以及激光与团簇相互作用诊断设备。给出了系统性能测试结果。      

High-speed processing with Cl2 cluster ion beam

Cluster ion beam processes can produce high rate sputtering with low damage compared with monomer ion beam processes. Cl₂ cluster ion beams with different size distributions were generated with controlling the ionization conditions. Size distributions were measured using the time-of-flight (TOF) method. Si substrates and SiO₂ films were irradiated with the Cl₂ cluster ions at acceleration energies of 10–30 keV and the etching ratio of Si/SiO₂ was investigated. The sputtering yield increased with acceleration energy and was a few thousand times higher than that of Ar monomer ions. The sputtering yield of Cl₂ cluster ions was about 4400 atoms/ion at 30 keV acceleration energy. The etching ratio of Si/SiO₂ was above eight at acceleration energies in the range 10–30 keV. Thus, SiO₂ can be used as a mask for irradiation with Cl₂ cluster ion beam, which is an advantage for semiconductor processing. In order to keep high sputtering yield and high etching ratio, the cluster size needs to be sufficiently large and size control is important.