低能高电荷态氮离子与Cu表面相互作用致K-X射线发射的研究  

Characteristics of K-shell X-ray emission in collisions of low-energy highly charged nitrogen ions with a Cu surface

作　　者：刘璇 宋张勇[1,4] 张秉章 钱程 方兴[1,4] 邵曹杰 王伟[1,4] 刘俊亮 徐俊奎[1,4] 冯勇 朱志超[3] 陈林 郭艳玲[2] 孙良亭 杨治虎[1] 于得洋 LIU Xuan;SONG Zhangyong;ZHANG Bingzhang;QIAN Cheng;FANG Xing;SHAO Caojie;WANG Wei;LIU Junliang;XU Junkui;FENG Yong;ZHU Zhichao;CHEN Lin;GUO Yanling;SUN Liangting;YANG Zhihu;YU Deyang(Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China;School of Nuclear Science and Technology,University of South China,Hengyang 421001,China;School of Nuclear Science and Technology,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]兰州大学核科学与技术学院,兰州730000 [3]南华大学核科学技术学院,衡阳421001 [4]中国科学院大学核科学与技术学院,北京100049

出　　处：《核技术》2021年第12期69-75,共7页Nuclear Techniques

基　　金：国家自然科学基金(No.11675279、No.12075291)资助。

摘　　要：利用中国科学院近代物理研究所的电子回旋共振离子源引出的高电荷态氮离子(N^(q+),q=3,5,6),在4.5~120 keV动能范围内系统测量了N^(q+)(q=3,5,6)与Cu表面碰撞产生的K-X射线能谱;基于原子壳层电离理论计算了K-X射线产额值及其电离截面值。结果表明:N^(q+)(q=3,5)离子进入靶表面后与Cu原子发生紧密碰撞,在直接库伦电离的作用下发射K-X射线,并且随着入射离子动能的增加,K-X射线产额和K壳层电离截面均单调增大;对于N^(6+)离子,K-X射线产额与其入射动能没有明显的依赖关系,且在Cu表面形成的"空心原子"级联退激产生的K-X射线产额约占其总K-X射线产额的97%。另外,N^(5+)离子入射时的K-X射线产额明显高于N^(3+)离子入射时的产额。本工作对离子与表面相互作用中形成的"空心原子"的退激过程具有重要的参考价值,并为理解"空心原子"的退激过程和彗星X射线机理的研究提供了基础数据。[Background]The highly charged nitrogen ions(N^(q+),q=3,5,6)are one of the main charged ions in the solar wind.Study of K-shell X-ray emissions in collisions of N^(q+)(q=3,5,6)ions with a Cu surface is of great significance for understanding the de-excitation process of"hollow atoms"and the generation mechanism of comet Xrays.[Purpose]This study aims to investigate characteristics of K-shell X-ray emission in impacts of N^(q+)(q=3,5,6)ions with a Cu surface.[Methods]The N^(q+)(q=3,5,6)ion beam was generated by the electron cyclotron resonance ion source(ECRIS)in Institute of Modern Physics,Chinese Academy of Sciences.The K-shell X-ray spectra resulted from collisions of the N^(q+)ions with the Cu surface were acquired by a silicon drift detector(SDD).Based on the Xray spectra,K-shell X-ray yields and ionization cross sections were calculated.[Results]The results show that,for the N^(q+)(q=3,5)ion incidence,K-shell X-ray emissions are attributed to close collisions of the ions with Cu atoms on the subsurface of the target,and that the K-shell X-ray yields and ionization cross sections increase monotonically with the increase of kinetic energy of the incident ions.For the N^(6+)ion incidence,the K-shell X-ray yields have no obvious dependence on kinetic energy of the incident ions.The K-shell X-rays are primarily emitted from the abovesurface of Cu target through the de-exciting of the formed"hollow N atoms",and they account for about 97%of the total X-rays.In addition,the X-ray yield of the N^(5+)ion incidence is higher than that of N^(3+)ions.[Conclusions]This study provides basic data for the understanding the de-excitation process of"hollow atoms"and the generation mechanism of comet X-rays.

关 键 词：X射线 高电荷态离子 X射线产额 电离截面 

分 类 号：TL99[核科学技术—核技术及应用]