-
报道了1.5—20 keV/q的高电荷态
$ {\rm{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${\rm{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${\rm{O}} ^{7+} $ 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$ {\rm{O}}^{7+} $ 离子的X射线产额相较于$ {\rm{O}}^{q+} $ (q = 3—6)离子高一个数量级, 不存在K壳层空穴的${\rm{O}} ^{6+} $ 离子的X射线产额也要高于$ {\rm{O}}^{3+} $ ,${\rm{O}} ^{5+} $ 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${\rm K}_{\text {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$1{\rm{s}} ^{2} $ 的$ {\rm{O}}^{6+} $ 离子与样品表面相互作用, 可能存在多电子激发使${\rm{O}} ^{6+} $ 离子产生K壳层空穴.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 ${\rm{O}} ^{q+} $ ions with aluminum surfaces. For the X rays emitted by$ {\rm{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${\rm{O}} ^{7+} $ ions mainly come from the decay of hollow atoms. Under the condition of equal kinetic energy, the X-ray yield of${\rm{O}} ^{7+} $ ions with K-shell vacancy is about one order of magnitude higher than that of$ {\rm{O}}^{q+} $ (q = 3, 5, 6) ions, and X-ray yield of$ {\rm{O}}^{6+} $ ions without K-shell vacancy is also significantly higher than that of${\rm{O}} ^{3+} $ and$ {\rm{O}}^{5+} $ 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 Kα-X rays of$ {\rm{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${\rm{O}} ^{6+} $ ions interacting with the sample, there may have a multi-electron excitation process that induces this K-electron ionization of the incident ions.-
Keywords:
- highly charged ion /
- X-rays /
- hollow atoms /
- kinetic energy threshold
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Li P F 2017 M. S. Thesis (Lanzhou: Lanzhou University) (in Chinese)
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-
图 1 高电荷态离子与表面相互作用实验装置示意图. 实验所需束流经偏转分析磁铁引出, 通过束流轮廓系统、束流密度计、电透镜、光栏后, 最终进入超高真空靶室
Fig. 1. Experimental diagram for interaction between highly charged ions and surfaces. The beam required for the experiment is led out by the deflection analysis magnet, passes through the beam profile system, the beam-current density meter, the electric lens, and the jaw slit, finally enters the ultra-high vacuum target chamber.
图 2 不同能量的
${\rm{O}}^{q+}$ (q = 3, 5, 6)离子入射Al表面产生的X射线谱 (a) 5—20 keV/q的${\rm{O}}^{3+}$ 离子; (b) 5—20 keV/q的${\rm{O}}^{5+}$ 离子; (c) 1.5—20 keV/q的${\rm{O}}^{6+}$ 离子. 箭头位置分别标示了C, O, Al的K壳X射线峰的标准值Fig. 2. X-ray spectra induced by
${\rm{O}}^{q+}$ (q = 3, 5, 6) ions impact on aluminum surfaces with varied energy: (a)${\rm{O}}^{3+}$ ions with incident energy of 5–20 keV/q; (b)${\rm{O}}^{5+}$ ions with incident energy of 5–20 keV/q; (c)${\rm{O}}^{6+}$ ions with incident energy of 1.5–20 keV/q. The arrow indicates the standard K-shell X-ray peak position of carbon, oxygen and aluminum, respectively.
图 3 1.5—20 keV/q的
${\rm{O}}^{7+}$ 离子入射Al表面产生的X射线谱. 箭头位置分别标示了C, O, Al的K壳X射线峰的标准值Fig. 3. X-ray spectra generated by
${\rm{O}}^{7+}$ ions impact on aluminum surfaces with the energy ranging from 1.5–20 keV/q. The arrow indicates the Standard K-shell X-ray peak position of carbon, oxygen and aluminum, respectively.
图 4 1.5—20 keV/q的
${\rm{O}}^{q+}$ (q = 3—7)离子入射Al靶产生O的K壳X射线产额Fig. 4. Bombardment of the aluminium target by
${\rm{O}}^{q+}$ (q = 3–7) ions with incident energy of 1.5–20 keV/q to produce K-shell X-ray yield of oxygen. -
[1] Hagstrum H D 1954 Phys. Rev. 96 336
Google Scholar
[2] Hagstrum H D, Becker G E 1973 Phys. Rev. B 8 107
Google Scholar
[3] Donets E D 1983 Phys. Scr. T3 11
Google Scholar
[4] Donets E D 1985 Nucl. Instrum. Methods Phys. Res. 9 522
Google Scholar
[5] Briand J P, Billy L D, Charles P, Essabaa S, Briand P, Geller R, Desclaux J P, Bliman S, Ristori C 1990 Phys. Rev. Lett. 65 159
Google Scholar
[6] Winter H, Aumayr F 1999 J. Phys. B: At. Mol. Opt. Phys. 32 R39
Google Scholar
[7] Burgdörfer J, Lerner P, Meyer F W 1991 Phys. Rev. A 44 5674
Google Scholar
[8] Schenkel T, Hamza A V, Barnes A V, Schneider D H 1999 Prog. Surf. Sci. 61 23
Google Scholar
[9] 周贤明, 尉静, 程锐, 赵永涛, 曾利霞, 梅策香, 梁昌慧, 李耀宗, 张小安, 肖国青 2021 物理学报 70 023201
Google Scholar
Zhou X M, Wei J, Cheng R, Zhao Y T, Zeng L X, Mei C X, Liang C H, Li Y Z, Zhang X A, Xiao G Q 2021 Acta Phys. Sin. 70 023201
Google Scholar
[10] 张小安, 梅策香, 张颖, 梁昌慧, 周贤明, 曾利霞, 李耀宗, 柳钰, 向前兰, 孟惠, 王益军 2020 物理学报 69 213301
Google Scholar
Zhang X A, Mei C X, Zhang Y, Liang C H, Zhou X M, Zeng L X, Li Y Z, Liu Y, Xiang Q L, Meng H, Wang Y J 2020 Acta Phys. Sin. 69 213301
Google Scholar
[11] Schuch R, Schneider D, Knapp D A, Dewitt D, Mcdonald J, Chen M H, Clark M W, Marrs R E 1993 Phys. Rev. Lett. 70 1073
Google Scholar
[12] Machicoane G A, Schenkel T, Niedermayr T R, Newmann M W, Hamza A V, Barnes A V, Mcdonald J W, Tanis J A, Schneider D H 2002 Phys. Rev. A 65 042903
Google Scholar
[13] Zhang H, Chen X, Yang Z, Xu J, Cui Y, Shao J, Zhang X, Zhao Y, Zhang Y, Xiao G 2010 Nucl. Instrum. Methods Phys. Res., Sect. B 268 1564
Google Scholar
[14] 张红强 2009 博士学位论文 (兰州: 兰州大学)
Zhang H Q 2009 Ph. D. Dissertation (Lanzhou: Lanzhou University) (in Chinese)
[15] 任惠娟, 张小安, 肖国青 2009 原子核物理评论 26 146
Google Scholar
Ren H J, Zhang X A, Xiao G Q 2009 Nucl. Phys. Rev. 26 146
Google Scholar
[16] 张小安, 肖国青, 杨治虎, 陈熙萌, 赵永涛, 李福利, 张艳萍, 崔莹, 张红强, 徐徐, 邵剑雄, 詹文龙 2006 中国科学 G刊 36 132
Zhang X A, Xiao G Q, Yang Z H, Chen X M, Zhao Y T, Li F L, Zhang Y P, Cui Y, Zhang H Q, Xu X, Shao J X, Zhan W L 2006 Sci. China, Ser. G 36 132
[17] 杨治虎, 宋张勇, 崔莹, 张红强, 阮芳芳, 邵剑雄, 杜娟, 刘玉文, 朱可欣, 张小安, 邵曹杰, 卢荣春, 于得洋, 陈熙萌, 蔡晓红 2008 物理学报 57 803
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Google Scholar
[18] 杨治虎, 宋张勇, 陈熙萌, 张小安, 张艳萍, 赵永涛, 崔莹, 张红强, 徐徐, 邵健雄, 于得洋, 蔡晓红 2006 物理学报 55 2221
Google Scholar
Yang Z H, Song Z Y, Chen X M, Zhang X A, Zhang Y P, Zhao Y T, Cui Y, Zhang H Q, Xu X, Shao J X, Yu D Y, Cai X H 2006 Acta Phys. Sin. 55 2221
Google Scholar
[19] Garcia J D 1970 Phys. Rev. A 1 280
Google Scholar
[20] Song Z Y, Yang Z H, Zhang H Q, Shao J X, Cui Y, Zhang Y P, Zhang X A, Zhao Y T, Chen X M, Xiao G Q 2015 Phys. Rev. A 91 042707
Google Scholar
[21] 李鹏飞 2017 硕士学位论文 (兰州: 兰州大学)
Li P F 2017 M. S. Thesis (Lanzhou: Lanzhou University) (in Chinese)
[22] Arnau A, Aumayr F, Echenique P M, Grether M, Heiland W, Limburg J, Morgenstern R, Roncin P, Schippers S, Schuch R 1997 Surf. Sci. Rep. 27 113
Google Scholar
[23] Magno C, Milazzo M, Pizzi C, Porro F, Rota A, Riccobono G 1979 Nuovo Cimento A 54 277
Google Scholar
[24] Gryziński M 1965 Phys. Rev. 138 A336
Google Scholar
[25] Center for X-ray Optics and Advanced Light Source, Lawrence Berkeley National Laboratory, X-Ray Data Booklet [EB/OL] http://xdb.lbl.gov/[2021-4-14]
[26] 张小安, 李耀宗, 赵永涛, 梁昌慧, 程锐, 周贤明, 王兴, 雷瑜, 孙渊博, 徐戈, 李锦玉, 肖国青 2012 物理学报 61 113401
Google Scholar
Zhang X A, Li Y Z, Zhao Y T, Liang C H, Cheng R, Zhou X M, Wang X, Lei Y, Sun Y B, Xu G, Li J Y, Xiao G Q 2012 Acta Phys. Sin. 61 113401
Google Scholar
[27] 梁昌慧, 张小安, 李耀宗 2013 原子核物理评论 30 63
Google Scholar
Liang C H, Zhang X A, Li Y Z 2013 Nucl. Phys. Rev. 30 63
Google Scholar
[28] Song Z Y, Yang Z H, Xiao G Q, Xu Q M, Yang Z R 2011 Eur. Phys. J. D 64 197
Google Scholar
[29] Hubbell J H, Trehan P N, Singh N, Chand B, Mehta D, Garg M L, Garg R R, Singh S, Puri S 1994 J. Phys. Chem. Ref. Data 23 339
Google Scholar
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