离子轰击引起的表面形貌对Ag的溅射产额的影响

用捕获膜技术和卢瑟福背散射(RBS)谱仪测定Ag靶在27keV Ar⁺离子轰击下的溅射原子角分布,从而确定不同剂量下Ag的溅射产额,并对其靶点表面形貌进行扫描电子显微镜(SEM)观察。结果发现,所有的角分布都呈over-cosine形状,但其溅射产额却随着表面形貌不同而不同。根据溅射产额Y与轰击离子入射角φ变化关系,讨论不同轰击剂量下溅射产额的差别,肯定了表面形貌是影响溅射产额的一个重要因素,并由此提出“表观产额”的新概念。 关键词：     

e+e－湮没过程的重子产生

本文指出(3/2)⁺与(1/2)⁺重子相对权重的改变对末态长寿命重子产额没有影响,而对(3/2)⁺重子产额改变显著.分析e⁺e^－实验资料发现对(3/2)⁺重子很强的抑制参数为0.3,由此得到的末态重子产额及产额比才能与实验符合.     

利用激光溅射原子束装置结合时间切片速度成像技术对于金属态-态反应动力学的相关研究

利用新建激光溅射交叉分子束装置,结合时间切片速度成像技术开展了金属原子态-态反应动力学的相关研究. 超声金属原子束是由激光溅射金属棒产生,结合无气体溢流通道的自由扩散设计,得到了质量很好的金属原子超声束. 本文选择Al+O₂反应体系来测试新建金属交叉分子束实验装置的性能. 通过(1+1) 共振多光子电离技术,以AlO(D²∑⁺)为中间态来探测特定转动态的产物AlO自由基. 相同波长下可以同时得到反应产物AlO(X²∑⁺,v=0,N和N+14)两个转动态的速度成像,分别对应着Δv=1的P(N)和R(N+14)跃迁. 在244.145 nm同时探测到P(15)和R(29)的跃迁,形成的两个环在切片成像图中可以完全区分开,这两个跃迁分别对应着反应产物AlO(v=0,N=15)和AlO(v=0,N=29)两个转动态. 对应此两个转动态的能级差为403 cm^-1. 这两个反应产物转动态的区分表明了该实验装置与最近的一篇研究报道[J. Chem. Phys. 140, 214304 (2014)]相比较,具有较好的碰撞能量分辨率.     

三氯一氟甲烷分子的正负离子对光解离动力学

在CFCl₃分子的同步辐射光激发正负离子解离过程中,利用负离子飞行时间质谱技术观测到了F^-和Cl^-(包括³⁵Cl^-和³⁷Cl^-),测量得到了³⁵Cl^-和³⁷Cl^-在7.75～22.00 eV的负离子产额效率谱. 实验得到CFCl₃→CFCl相似文献   

Cl(2P)+D2→DCl+D反应中波恩-奥本海默近似有效性的交叉分子束研究

本文利用高分辨的里德堡态氘原子标识-交叉分子束装置，研究了碰撞能为4.5∽6.5 kcal/mol范围内Cl(²P)[Cl(²P_3/2)和Cl^*(²P_1/2)]与D₂的反应. 虽然自旋轨道激发态反应Cl^*(²P_1/2)+D₂在波恩-奥本海默(B-O)近似下本应是禁阻的，但实验中观测到了该反应的贡献. 通过测量靠近后向的碰撞能相关的微分散射截面连线，发现低碰撞能下的产物主要来自于B-O近似禁阻的反应Cl^*+D₂. 随着碰撞能的提高，自旋轨道基态反应Cl+D₂的反应性增加明显要比自旋轨道激发态反应Cl^*+D₂更快，并且在高碰撞能下成为产物的主要来源. 实验结果表明：在低碰撞能下，Cl^*中自旋轨道激发态的额外能量，可以帮助B-O近似禁阻的反应Cl^*+D₂越过势垒；然而当碰撞能接近和高于反应势垒时，B-O近似允许的反应Cl+D₂占主导地位. Cl/Cl^*+D₂反应中B-O近似有效性的特征与其同位素反应Cl/Cl^*+H₂是一致的.     

Al-50wt% Sn合金的离子溅射研究

用捕获膜技术和卢瑟福背散射(RBS)分析,测定Al-Sn多相合金在30keV Ar⁺离子轰击时Al和Sn的溅射原子角分布。溅射后的样品用扫描电子显微镜(SEM)进行观察,并用电子微探针分析仪(EPMA)对轰击样品(靶点)和未轰击样品作成分分析。结果表明,Al的溅射原子角分布近于cosine形状,而Sn却是over-cosine型角分布。本文给出一个按不同表面形貌特征划分的各元素富集区i进行叠加的产额表达式,Y(θ)=∑Y_i(θ),解释了实验结果。 关键词：     

部分子末态的色分离联接对e+e－反应中强子产额及其动量谱的影响

用JETSET事例产生器对e⁺e^－→qq+ng→hadrons反应中,末态部分子(qq+ng)以色分离的联接方式进行强子化时,各种强子产额及π⁺,K^±,p/p的动量谱进行了计算;与传统的色中性流联接方式强子化结果进行比较.结果表明:由T权重确定的色分离单态和色中性流这两种完全不同的色联接方式强子化得到的强子产额及π⁺,K^±,p/p的动量谱,与实验符合的程度相同,有些更好.     

聚变α粒子对第一壁辐照损伤的蒙特-卡罗研究(Ⅱ)——溅射

本文应用蒙特-卡罗方法研究聚变α粒子对不锈钢第一壁的溅射损伤。首先,计算单种元素Fe,Cr,Ni的溅射产额随入射能量的变化,并与实验结果比较,以确定计算中所用到的一些重要参数,如原子位移能等。在此基础上计算聚变α粒子对不锈钢(Fe_0.73Cr_0.18Ni_0.09)的部分(和总)溅射产额,溅射粒子的能谱、角分布和源深度分布,以及上述各量与α粒子入射角的关系。结果表明,在考虑入射α粒子随能量及入射角的分布后,其平均总溅射产额为0.375。由于1     

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采用分子动力学模拟方法研究了样品温度对Ar+与SiC样品表面相互作用的影响。由模拟结果可知,SiC样品中Si原子的溅射产额随着温度的升高而增加,而温度对C原子的溅射产额影响不大。在相同温度下,Si原子的溅射产额要高于C原子的溅射产额。溅射出来的Si原子和C原子主要来源于样品的表层区域,样品中的Si和C原子密度、键密度及它们的成键方式也发生了较大的变化。初始样品中Si和C原子的密度是均匀的,而被轰击过后的样品表面Si原子的密度要高于C原子,而样品中部C原子的密度要高于Si原子。初始样品都是Si-C键,成键方式为Si-Csp3;被轰击过后又有Si-Si和C-C键,成键方式也发生了变化,还有Si-Csp1和Si-Csp2。     

高电荷态离子与SiO2表面相互作用的研究

高电荷态离子(Pbq ,Arq )由兰州近代物理研究所的ECR实验平台所产生,轰击非晶态SiO2表面.用微通道板测量溅射粒子产额的角分布.用公式拟合实验溅射角分布得到了较好的结果,并给出了初步的理论解释.由此得出了高电荷态离子与SiO2表面作用的微分溅射截面.实验结果表明高电荷态离子能够增加动能溅射;同时高电荷态离子入射能够引起势能溅射.在大角度入射时,溅射产额主要是由碰撞引起的;在小角入射时势能溅射所占比重会增大.     

The Nonlinear Enhancement Effect of Sputered Ag-atoms With FeCl+ Bombardment

Measurements of the angular distributions and yields of atoms sputtered from Ag target by bombardment with FeCl⁺,⁵⁶Fe⁺ and ³⁵Cl⁺ are reported.Large enhancement occurs in the measured Ag atom yield for FeCl⁺ projectile in comparison with the sum of the sputtering yields for ⁵⁶Fe⁺ and ³⁵Cl⁺ bombardment at same impact velocities.The enhanecment can be explained by a model of the thermal spike-evaporation plus surface topography effect.     

Ag/Fe/Ag 纳米颗粒膜磁特性和微结构

"利用对靶磁控溅射法制备了一系列Ag/Fe/Ag纳米薄膜,沉积态样品Fe层厚度固定为35 nm,Ag层厚度为1、2、3、4、5 nm．随后对沉积态样品进行了退火处理,退火温度分别为200、300、400、500、600 ℃ , 退火30 min． 利用VSM测量了样品的磁特性, 利用SPM观察样品表面形貌和磁畴结构,并且利用XRD分析了样品的晶体结构．研究结果表明,沉积态样品随Ag层厚度的变化,垂直和平行膜面矫顽力均先增加后减小．当Ag层厚度为3 nm时,垂直膜面矫顽力最大约为260 Oe,样品颗粒分布均     

Study on the orientation of silver films by ion-beam assisted deposition

Low energy ion beam assisted deposition (IBAD) was employed to prepare Ag films on Mo/Si (100) substrate. It was found that Ag films deposited by sputtering method without ion beam bombardment were preferred (111) orientation. When the depositing film was simultaneously bombardment by Ar⁺ beam perpendicular to the film surface at ion/atom arrival ratio of 0.18, the prepared films exhibited weak (111) and (200) mixed orientations. When the direction of Ar⁺ beam was off-normal direction of the film surface, Ag films showed highly preferred (111) orientation. Monte Carlo method was used to calculate the sputtering yields of Ar⁺ ions at various incident and azimuth angles. The effects of channeling and surface free energy on the crystallographic orientation of Ag films were discussed.     

快中子引起的背向溅射

描述了用实验方法测量快中子引起的背向溅射,测量了Mg、Al、Sc、V、Fe、CO、Cu、Zr、Au和316型不锈钢等10种材料的背向溅射产额,并与正向产额进行了比较,发现背向和正向溅射产额的比值与核反应的类型有关.本实验的结果同其它小组的结果进行了比较,并用溅射理论对实验结果进行了解释.     

Proton beam enhanced adhesion of iron films

Depth-selective surface Mössbauer and adhesion measurements were pertormed on as evaporated and proton bombarded⁵⁷Fe and⁵⁶Fe/⁵⁷Fe films supported by glass and fused silica. The results contribute to the understanding of the mechanism responsible for adhesion enhancement of metallic films induced by ion bombardment in the electronic stopping region.     

Controllable p-doping of graphene on Ir(111) by chlorination with FeCl3

The in situ chlorination of graphene on Ir(111) has been achieved by depositing FeCl(3) followed by its thermal decomposition on the surface into FeCl(2) and Cl. This process is accompanied by an intercalation of Cl under graphene and formation of an epitaxial FeCl(2) film on top, which can be removed upon further annealing. A pronounced hole doping of graphene has been observed as a consequence of the annealing-assisted intercalation of Cl. This effect has been studied by a combination of core-level and angle-resolved photoelectron spectroscopies (CL PES and ARPES, respectively), near-edge x-ray absorption fine structure (NEXAFS) spectroscopy and low-energy electron diffraction (LEED). The ease of preparation, the remarkable reproducibility of the doping level and the reversibility of the doping upon annealing are the key factors making chlorination with FeCl(3) a promising route for tuning the electronic properties in graphene.     

Spike effects in heavy-ion sputtering of Ag,Au and Pt thin films

Sputtering yields of Ag, Au and Pt have been measured for monatomic and polyatomic ions of P, As, Sb and Bi over the energy range 10–250 keV. Large enhancements of the measured sputtering yields over those predicted by cascade theory occur for the very heavy ion bombardments. These enhancements become much larger for polyatomic ion bombardment and are strongly non-linear with the number of atoms comprising the molecule. The high sputtering yields are consistent with a major contribution due to a highly disrupted surface region and an associated reduction in the surface binding energy. They cannot be explained using a thermal spike model in which the enhancement results from a localized evaporation.     

X-ray production by Pt and Os projectiles moving in thick Fe targets withE p =17−30 MeV

X-ray spectra produced by Pt and Os bombardment of Fe targets have been measured in the projectile energy range ofE _p =17 to 30 MeV. The thick target yields of the Fe K-shell and Pt and Os M-shells were analyzed within the Landau-Zener model. M-vacancy fractions, their respective lifetimes, and the level-crossing radii for the Pt−Fe and Os−Fe encounters were deduced. The results are discussed with emphasis on the mechanism of transient magnetic fields.     

Major improvements of the photorefractive and photovoltaic properties in potassium niobate

Optical and electrical measurements have been made on a new codoped potassium niobate crystal (KNbO3:Fe,Ag) that yields a significant enhancement of the photorefractive and photovoltaic effects when compared with the published results for singly doped potassium niobate crystals. The codoped Ag impurity enters the K site, rather than the typical Nb site, thus changing the local field in the lattice. It is believed that Fe perturbed by the Ag in the K site is responsible for an enhancement of the linear absorption and photocurrent, as well as a probable increase in the effective trap density. An enhanced trap density is likely the cause of the increased photorefractive counterpropagating two-beam coupling efficiency.     

Simultaneous ejection of two molecular ions from keV gold atomic and polyatomic projectile impacts

We present the first experimental data on the simultaneous ejection of two molecular ions from the impact of Au(+)(n) (1< or =n< or =4) with energies ranging between 17 and 56 keV. The yields from single phenylalanine (Ph) emission, coemission of two Ph ions, and emission of the Ph dimer were measured. Large increases (1 to 2 orders of magnitude) in coemitted ion yields were observed with increasing projectile energy and complexity. Correlation coefficients were calculated for the coemission of two Ph ions; their behavior suggests differences in emission pathways for bombardment by atomic and polyatomic projectiles.