类氦镁离子、类铍离子的能级结构和光谱跃迁的理论研究

【作者】 杨天丽；

【导师】 谭明亮；

【作者基本信息】 四川大学 ， 原子与分子物理， 2001， 硕士

【摘要】 本论文根据全相对论多组态Multi-configuration Dirac-Fock理论，采用Grant的多组态Dirac-Fock的程序包GRASP~2(General-Purpose Relativistic AtomicStructure Program 2 1992)，系统地研究了类铍等电子序列(Z=5-92)的高激发态禁戒跃迁的光谱特性；类氦镁、类氦铝离子的能级结构以及镁的各阶电离势。全文共由六章组成：第一章简单地介绍了近几十年来高离化原子离子在理论和实验两方面所取得的研究进展。第二章叙述了研究高离化原子离子能级结构与光谱跃迁的基本理论方法。第三章系统地研究了类氦镁、类氦铝离子的精细能级结构、类氦镁的部分电偶极跃迁及镁的各阶电离势。第四章系统地研究了类铍离子的禁戒跃迁(1s22p3d)l—(1s22p面o、(1s22p4d)l—(1s22p3面。的能级间隔和光谱数据。第五章对类铍钨离子在(1s22p3d)l与(1s22p3d)0之间、(1s22p4d)l与(1s22p3d)0之间产生X-ray激光的可能性进行了分析。第六章是对上述工作的总结。 高离化原子离子光谱是研究原子结构、高温等离子体中的原子物理过程以及等离子体诊断技术的基础，是当前原子分子物理研究的前沿。低、中Z元素离子光谱数据已较为全面，但对高Z元素的高离化离子的高激发态的光谱研究还相当缺乏，尚待填补。本文计算的类铍离子的磁偶极(1s22p3d)l—(1s22p石)o、(1s22p4d)l—(1s22p3面。跃迁的能级间隔、自发跃迁几率和加权振子强度等光谱数据、类氦镁离子的电偶极跃迁的自发跃迁几率和加权振子强度，在这方面填补空白。计算中考虑了breit修正、QED修正及核的有效体积效应。研究表明： (1)在类氦镁、类氦铝离子的能级结构计算中，相对论效应、breit修正及QED修正使得部分能级发生交错和倒置，breit修正和QED修正在能量中占有很大的比例。这两种修正在高离化重元素离子的计算中应考虑。 (2)计算镁的电离势时，电子相关作用对计算结果影响较大，若计算中考虑了相关能使得计算结果更接近实验值。 (3)类氦镁的电偶极跃迁表明：高离化离子的光谱线非常密集，对某一特定的线系，自发跃迁几率和加权振子强度随着激发态主量子数n的增加而减少，在高离化原子中由于相对论效应，使得违反LS耦合选择定则的跃迁因满足jj耦合选择定则成为可能。 (4)首次从理论上得到了类铍离子的磁偶极(1s22p3d)l—(1s22p3d)0、磁偶 四川大学硕士论文 极（IS22P4d）l叶IS22P3d）。跃迁的能级间隔、自发跃迁系数和加权振子强 度。其中能级间隔随着核电荷数Z增加而增大，增长速率远比类被 离子电偶极跃迁的能级间隔增长快得多。对于自发跃迁系数而言， 在低Z段元素离子其值很小，随着核电荷数增加急剧变大，以致在 重元素离子区己达到 10’量级，与中性原子的电偶极跃迁相当，在整 个等电子序列计算中的增长速率远比电偶极跃迁增长的快，这一点 与电偶极跃迁有区别。 （5）通过对钨等离子体中的主要物理过程的计算分析可知：在零密度场 下，仅从双电子复合过程出发，可能在（Is勺p3d）；和（Is勺p3d儿， （l勺；和（Is勺 人之间产生相应的X－fsy激光光谱，但强度很 弱；若计及其他物理过程，则激发态之间很难产生X｛ay激光光谱。 在考虑外强场（电场、光强）条件下，双电子复合过程有可能比 其他的物理过程更显著，在双电子复合机制下产生相应的X寸ay激 光的可能性还是存在。但具体的结果还有待于从理论和实验两方 面做进一步地研究。重要的是，由朱正和教授和叶安培博士提出 的“在合适的泵浦机制下产生非电偶级的X－y激光谱线”这一新 观点为寻找最佳泵浦机制和新的激光工作物质提供了一个新的发 展方向。 上述计算的类氦、类镀离子的原子结构和光谱数据将有助于实验物理工作者在激光等离子体诊断领域中对仍未观察到的类氦、类披等离子体谱线的辨认，并为这方面提供深入的理论和实验推动作用。更多还原

【Abstract】 In this paper, the forbidden transition data of excited states for Like-Be ions (Z=5-92), the energy structure of Like-He Mg10"1", AL11+and the ionization energy of metal Magnesium have been calculated systematically by the fully relativistic multiconfiguration Dirac-Fock method. This consist of six chapters, which in chapter 1 we have introduced simply the progress of and main theoretical method of highly ionized ions in theoretical and experimental, in chapter 2-3,the fundamental theoretical method are generalized, in chapter 4, We study systematically the energy structure for Mg10+and AL11+, the spectra transition data of electric dipole about the two -ions and ionization energy of metal Magnesium, the energy intervals, Einstein coefficients and weighted oscillator strengths of magnetic dipole (Mi) (Is22pld\-(ls22p3d)0, (\s22p4d\-(\s22p3d)0 have been systematically studied in chapter 5.In addition,We have analyzed the feasibility of producing X-ray laser between (Is22p3d)i and (1s22p3d)0 .between (Is22p4d\ and (Is22p3rf)0 .The last one have drawed conclusion about the above works.The highly ionized atoms spectroscopy are the basis of studying atomic structure, physic procedure of high temperature plasma and plasma diagnosis technology . These are on the theoretical front and the data are the inevitable basis data in ICF and MCF.The spectra data about low Z and middle Z ions are complete, but those of highly Z elements and heavy ions are rare. Based on multiconfiguration Dirac-Fock approach with breit and QED correction the energy separation and spectra data such as spontaneous transition probability and weightedIVoscillator strength of magnetic dipole for isoelectronic sequence Be. The results indicated that (1) relativistic effect, breit and QED correction have made partial energy order changed. These can not be ignored in treating highly stripped ions. (2) Because the electronic correction has effected on the calculation results, the data about ionization energy of Mg including the electronic correction are more agreement with the experimental result. (3) The transition data of EI for Like-He Mg10+ indicated that the spectra lines are intensive. To a certain , as the qutatum number increse the transition probability and oscillator strength decrease. In addition, it is possible for transition that satisfies the JJ rule but LS rule. (4) We first obtain the spectra transition data of magnetic dipole (Mi) (ls22/>3</), - (Is22p3d)0 , (Is22p4d\ -(\s22p3d)0foT Like -Be ions. The energy intervals increase with atomic nuclei number and the increasing rate of energy intervals for MI is quicker than that of energy intervals for EI .For transition probabilities, though that of low Z is small, for heavy ions it has reach 107 quantity which nutral atomic probability is so in generalist increasing regular is the same as that of energy intervals. (5) We have analyzed the feasibility of producing X-ray laser lines between the above levels.The results indicate that it is difficult to obtain the popular reverse and X-ray laser lines because the rate of direct combination is 10 times larger than that of dielectric combination and the reverse can not be obtained by the direct combination without taking external stimuli factors into account. But the new idea which X-ray laser line of for-bidden transition should be produced in a suitable pump mechanism has point out a new development direction for finding the best pump directcombination and new laser media.更多还原