高电荷态离子207Pb36+与金属Nb表面作用产生的二次离子产额

本文报道了利用兰州重离子加速器国家实验室的ECR离子源引出的高电荷态离子207Pb36 入射到金属Nb表面产生的二次离子的实验测量结果.实验发现,二次离子产额Y随入射初动能Ek的增加有先增加后减小的关系,在初动能为576 keV时二次离子产额达到最大.通过对实验点做高斯拟合发现,曲线峰值对应的入射初动能为602 keV.分析表明,这是势能沉积作用与线性级联碰撞过程协同作用的结果.高电荷态离子本身携带的高势能沉积在靶表面引起势能溅射,促进了二次离子的发射;而主导二次离子溅射的过程是动能溅射,它与靶表面的动量沉积(核能损)过程密切相关.

Emission of secondary ions from metallic Nb surface by highly charged 207Pb36+ ions

The secondary ion emission induced by highly charged()~(207)Pb~(36 ) ions interacting with a metallic niobium surface is reported.The projectile ions,were provided by the Electron Cyclotron Resonance(ECR) ion source in the National Laboratory of the Heavy Ion Reaearch Facility in Lanzhou(HIRFL).It is found that the secondary ion yield was firstly increasing and then decreasing with the increase of the projectile kinetic energy.The secondary ion yield has a maximum value when the projectile kinetic energy is 576 keV.We fitted the experimental data using Gaussian Function and found that the projectile kinetic energy corresponding to the fitting curve peak is 602 keV.Analyses show that this process is the synergy of the potential deposition and linear cascade collision.The high potential energy of the highly charged ions deposited in the target surface aroses the potential sputtering,and promotes the emission of secondary ions.However,the predominant process of secondary ion sputtering is kinetic sputtering,which closely related to the momentum deposition on the target surface(nuclear stopping power).