【摘要】 报道了 1.5—20 keV/q的高电荷态O^q+（q=3—7）离子与Al表面相互作用发射的O原子的特征X射线谱.分析表明,对于O^q+（q=3—6）离子入射时发射的X射线,是由于离子进入表面后与Al原子发生紧密碰撞导致的;而O⁷⁺离子入射时的X射线,主要来自于"空心原子"的衰变.在动能相等的条件下,存在K壳层空穴的O⁷⁺离子的X射线产额相较于O^q+（q=3—6）离子高一个数量级,不存在K壳层空穴的O⁶⁺离子的X射线产额也要高于O³⁺,O⁵⁺离子.总体来说,X射线产额以及电离截面与入射离子的初始电子组态有关,且随离子入射动能的增加而增加.根据半经典两体碰撞模型,本文估算了入射离子与靶原子相互作用时分别产生O和Al的K_α-X射线的动能阈值.对于入射动能低于动能阈值且电子组态为1s²的O⁶⁺离子与样品表面相互作用,可能存在多电子激发使O⁶⁺离子产生K壳层空穴.更多还原

【Abstract】 The interaction of highly charged ions with solid surfaces is a very complex multi-body process.When the ions are close to the solid surfaces,the potential energy of the ions will be deposited in a tiny area of the target surfaces in a short time and then emitting X rays,which has important scientific significance and application in Astrophysics and plasma diagnosis.For experiments on the interaction of highly charged ions with surfaces,not only the X-ray energy spectrum but also the X-ray yield should be measured accurately.The precise measurement of the X-ray yield depends on the ability to accurately measure the beam-current intensity.In the past,the beam-current intensity was acquired by measuring the target current.Since the interaction between highly charged ions and solids involves the emission of secondary electrons,the actual measured target current is the sum of the initial beam-current intensity and the intensity caused by the secondary electrons,resulting in inaccurate X-ray yield calculations.In this experiment,a new analytical device,beam-current density meter,has been designed,which can measure the beam-current intensity with an accuracy of 0.1 nA.By measuring the current on the density meter instead of the target current,the influence of secondary electrons is almost avoided,and a more accurate X-ray yield is obtained.This paper reports the characteristic X-ray spectra of oxygen atoms emitted from the interaction of 1.5-20 keV/q highly charged O^q+ ions with aluminum surfaces.For the X rays emitted by O^q+（q=3,5,6） ions,the experimental results show that it is due to the close collisions with aluminum atoms after entering the surfaces,while the X rays emitted by O⁷⁺ ions mainly come from the decay of hollow atoms.Under the condition of equal kinetic energy,the X-ray yield of O⁷⁺ ions with K-shell vacancy is about one order of magnitude higher than that of O^q+（q=3,5,6） ions,and X-ray yield of O⁶⁺ ions without K-shell vacancy is also significantly higher than that of O³⁺ and O⁵⁺ ions.Generally,the X-ray yield and ionization cross-section is associated with the initial electron configuration of incident ions,and increases with the growth of ions kinetic energy.Based on the semi-classical approximation theory of binary collision,we have estimated the kinetic energy threshold for the emission of the K_α-X rays of O^q+（q=3,5,6） ions as interacting with the aluminum target.As the incident kinetic energy is lower than the kinetic energy threshold,for O⁶⁺ ions interacting with the sample,there may have a multi-electron excitation process that induces this K-electron ionization of the incident ions.更多还原