溅射原子角分布的同位素效应

本文报道了用50keV Ar~+离子在垂直入射情况下对Cu元素进行溅射的实验。研究了作为发射角函数的同位素富集行为。结果表明,较轻的同位素无富集,而较重的同位素在从～5°到80°发射角范围内都是富集的。     

27keV Ar~+斜入射时的Cu-Au合金溅射实验角分布

用27keV Ar~+分别在垂直和倾斜入射情况下,轰击了Cu-Au(30wt％)合金样品,测量了Cu和Au原子的溅射角分布。角分布是用卢瑟福背散射(RBS)技术分析Al捕获膜上的Cu-Au沉积成分而定量得到的。结果表明:(1)在Ar~+倾斜(θ=40°)入射时,Cu原子择优发射,且程度比垂直入射(θ_r=O°)时增强:(2)倾斜入射时,Cu原子的角分布显示出在接近于样品表面法线方向的发射角范围内(θ<45°),发射机率比垂直入射时减小。     

Ar离子轰击Ag靶的溅射角分布

本文描述了用溅射粒子捕集器和Rutherford背散射分析测定溅射粒子角分布的实验方法。给出了100keV Ar~+在入射角分别为0°、30°、50°和80°时轰击Ag靶的溅射角分布。角分布偏离余弦形状,有前倾趋势。溅射产额随入射角增大而迅速增加。由50keV Ar~+垂直入射Ag的溅射角分布计算出的总溅射产额为16.8±2.4~(atoms)/Ar~+。实验结果与理论值进行了比较,并作了定性分析。     

Cu－37at％ Ag共晶合金的离子溅射研究

侧重研究了入射Ａｒ＋离子不同剂量轰击时表面微形貌和溅射原子角分布之间的关联，并建议用“元素按靶点表面微形貌特征局域富集模型”来解释溅射原子角分布形状以及择优溅射曲线的变化；发现其结果与实验相符合。     

关于Cu-Au合金溅射机制的研究

本文报导了用热中子活化分析法测量在不同剂量Ar~+离子轰击下Cu-Au合金的溅射产额     

100keV Ar~+、Ne~+轰击铜靶所产生的溅射原子角分布与离子入射角的关系

在40°和70°斜入射条件下,用100keV Ar~+、Ne~+轰击铜靶,Ar~+所产生的溅射原子角分布的溅射优先方向分别位于表面法线的两侧,溅射原子角分布对于表面法线明显不对称;而Ne~+所对应的溅射优先方向都位于表面法线方向,且溅射原子角分布对于表面法线是对称的。用级联碰撞理论分析了所得到的实验结果,并比较了Ar~+和Ne~+溅射机制上的不同。     

Angular distribution of sputtered atoms induced by low-energy heavy ion bombardment

The sputtering yield angular distributions have been calculated based on the ion energy dependence of tohal sputtering yields for Ni and Mo targets bombarded by low-energy Hg^ ion. The calculated curves show excellent agreement with the corresponding Wehner‘s experimental results of sputtering yield angular distribution. The fact clearly demonstrated the intrinsic relation between the ion energy dependence of total sputtering yields and the sputtering yield angular distribution. This intrinsic relation had been ignored in Yamamura‘s papers (1981,1982) due to some obvious mistakes.     

27keV Ar~+离子溅射Cu和CuAu靶时Cu的同位素分馏研究

本文报道了27keV Ar~+离子分别轰击Cu元素靶和CuAu合金靶时溅射Cu原子的同位素(~(63)Cu和~(65)Cu)分馏测量结果,发现:(1)对Cu元素靶,同位素分馏δ_f(~(63)Cu,~(65)Cu)=(62±27)‰,而对Cu-Au合金靶,δ_f=(5.9±1.6)‰;(2)δ_f(~(63)Cu,~(65)Cu)随发射角θ的变化对两者靶而言趋势是相似的,但在CuAu合金靶情况下,当θ≤40°时,δ_f((63)Cu,~(65)Cu)为负值。     

The angular distribution of particles sputtered from Cu,Zr, and Au surfaces by ion bombardment at grazing incidence

The angular distribution of particles sputtered from polycrystalline Cu, Zr, and Au targets has been measured for bombardment with Ar⁺- and Xe⁺-ions at perpendicular and grazing ion incidence (80° and 85° with respect to the surface normal). The ion energy was varied between 100 keV and 900 keV. The measured distributions follow approximately a cosine-squared curve rather than the cosine function, they are found to be symmetric with respect to the surface normal and almost independent of the ion species, the ion energy and the angle of incidence. Values of sputtering yield of Cu, Au and Zr are also presented.     

Resonant mechanisms for negative ionization of secondary emitted atoms from sputtered metals

A model is presented to describe negative ionization of low energy, secondary atomic particles ejected from sputtered metal surfaces. Focus is made on the diatomic systems formed, in the collision cascade generated by the primary ion beam, between secondary emitted atoms and their nearest-neighbor substrate atoms that provide the initial impulse for ejection. Two different resonant ionization mechanisms are investigated such that a conduction electron may tunnel into the affinity orbital of the ejected atom either by direct hopping or after an intermediate transition via the affinity orbital of the substrate atom. A numerical method is outlined to calculate the negative ionization probability of secondary emitted atoms. A good agreement is found with van Der Heide’s measurements of the Cu⁻ population sputtered from a clean Cu-surface, at emission energies below 100 eV.     

The charge state distribution of B,C, Si,Ni, Cu and Au ions on 5 MV pelletron accelerator

Stripper gas and terminal potential play a key role for the charge state distribution in a tandem pelletron accelerator. The knowledge of this distribution is important for experiments performed on tandem accelerators. The charge state distribution of B, C, Si, Ni, Cu and Au beams is measured by using Ar as stripper gas, and terminal potential is varied from 0.3 to 3.0 MV on 5UDH-2 tandem pelletron accelerator installed at the National Centre for Physics, Islamabad. The individual charge state is measured after the switching magnet at 15° in high-energy portion. It is observed that the higher charge states are stable in the range of lower and middle atomic masses of periodic table, whereas higher atomic mass(Au) shows beam current instability in higher charge states. For carbon,the charge distribution at 1.7 MV terminal potential by varying stripper gas pressure is also studied, which resulted in decreased overall transmission with good current value for higher charge states.