铬、铥和铕原子离子激发态辐射参数和朗德因子实验研究

发布时间：2018-06-01 13:52

本文选题：时间分辨激光诱导荧光 + 量子拍光谱　；参考：《吉林大学》2016年博士论文

【摘要】：原子离子的结构参数和辐射参数是原子物理学、分析化学、等离子体物理和天体物理学等学科领域研究所需的基础数据。原子物理领域中,能级的自然辐射寿命和朗德因子是人们了解原子结构、电子动力学过程、角动量耦合图像和激发态原子辐射性质的基本信息。天体物理学领域中,精确的振子强度等辐射参数在分析天体演化过程、确定化学元素丰度和了解恒星核合成过程等问题中亦有其重要作用。据文献报道,稀土元素和铁峰元素在化学特殊星、炽热恒星等天体上有较高丰度,因此对其所属元素辐射参数进行研究与分析是很有必要的。本文利用时间分辨激光诱导荧光(TR-LIF)方法、量子拍光谱方法和激光烧蚀技术,确定了铬原子的朗德因子和自然辐射寿命,铥原子、铥一价离子和铕二价离子的自然辐射寿命。寿命测量过程中,用倍频、三倍频和受激拉曼散射等手段获得可见及紫外波段的激发光;在真空室中,基态或亚稳态的原子或离子被激发到目标能级;由该能级向下自发辐射的荧光经由聚焦透镜、光栅单色仪和光电倍增管组成的探测系统进行探测,然后传输到示波器中显示并记录;最后对荧光衰减曲线进行e指数或解卷积拟合,确定能级的自然辐射寿命。合理地选择磁场大小和适当地调节偏振方向,荧光信号出现振荡,即产生量子拍衰减信号。然后对量子拍曲线进行傅立叶变换得到量子拍频,进而确定能级的朗德因子。在实验过程中,通过使用不同的激发方案,改变观测通道和延迟时间等方法,排除共激发的干扰,确保目标能级被准确激发。通过调节各种实验条件(如:激发和烧蚀光能量、烧蚀激光焦点大小、磁场强度和激发-烧蚀光之间的延迟时间等),消除各种物理效应(如辐射陷阱效应、超辐射效应、量子拍效应、饱和效应、碰撞效应和飞出视场效应等)可能对寿命测量产生的影响。寿命结合分支比是一种确定跃迁几率和振子强度的可靠方法。分支比测量方面,以空心阴极灯作为原子或离子谱线的发射源,由高分辨率光栅光谱仪测量发射谱,然后对跃迁谱线进行拟合分析,用谱线的强度比来确定跃迁分支比。本论文具体内容包括以下三个部分:一、运用TR-LIF方法和和量子拍光谱方法,测量了Cr I 3d54p、3d44s4p、3d55p和3d44s5p组态,能级位于23305.0026-53782.78 cm-1之间35条奇宇称能级的朗德因子和43条奇宇称能级的寿命。其中15个朗德因子和17个能级寿命属于首次测量。测得的寿命值在11.4-193 ns范围之间。把实验测量g因子值与不同纯耦合方式下的g值进行对比,发现所研究能级的耦合方式更接近LS耦合。此外,利用铬空心阴极灯的原子发射谱,确定了8条铬原子跃迁的分支比,并结合寿命数据确定了31条谱线的跃迁几率和振子强度。二、运用TR-LIF方法,测量了Tm I的4f125d6s6p、4f126s26p、4f136s8s、4f125d6s2、4f136s6p、4f136s7p、4f135d6p、和4f136s8p组态位于22791.176到48547.98cm-1之间88个激发态能级的自然辐射寿命,寿命值分布在15.4-7900 ns之间,其中77个能级属于首次研究报道。还测量了Tm II的4f126s6p、4f125d6p、4f125d6s、4f125d2和4f126s2组态位于27294.79到65612.85 cm-1之间29个能级的自然辐射寿命,寿命值分布在36.5-1000 ns之间,其中22个能级属于首次报到。另外,对15个Tm II能级的位置进行了修正。三、利用TR-LIF方法,测量了Eu III 4f 6(7F)5d组态位于39636.83到42530.91cm-1之间6条偶宇称能级的自然辐射寿命,其中3条能级属于首次测量。它们的寿命值在33-130 ns之间,寿命误差都在10%以内。综上所述,本文对铬原子(Cr I)能级的自然辐射寿命、朗德因子和跃迁分支比进行了测量研究,并确定了分支比测量谱线的振子强度;另外,还测量研究了铥原子(Tm I)、铥一价离子(Tm II)和铕二价离子(Eu III)能级的自然辐射寿命,得到了一批文献中未见报道的新的原子辐射和朗德因子参数。这些原子数据不仅为确定天体中化学元素丰度提供丰富的光谱分析数据,还对核聚变物理、原子物理和等离子体物理等领域相关问题的研究具有重要的科学价值。
[Abstract]:The structural parameters and radiation parameters of atomic ions are the basic data needed in the field of atomic physics, analytical chemistry, plasma physics and astrophysics. In the field of atomic physics, the natural radiation life of the energy level and the Lund factor are the understanding of the atomic structure, the electron dynamics process, the angular momentum coupling image and the excitation. The basic information of the properties of the atomic radiation. In astrophysics, the exact intensity of the vibrator and other radiation parameters also play an important role in the analysis of the evolution of the celestial bodies, the determination of the abundance of chemical elements and the understanding of the process of the synthesis of stars. With high abundance, it is necessary to study and analyze the radiation parameters of its elements. In this paper, a time resolved laser induced fluorescence (TR-LIF) method, a quantum beat spectrum method and a laser ablation technique have been used to determine the natural radiation life of the chromium atom and the natural radiation life, thulium, thulium and europium two valence ions. In the course of life measurement, the excitation of visible and ultraviolet bands is obtained by means of frequency doubling, three frequency doubling and stimulated Raman scattering; in the vacuum chamber, the atoms or ions of the ground state or metastable state are excited to the target level; the fluorescence of the spontaneous emission downward from the energy level is via the focusing lens, the grating monochromator and the photomultiplier group. The detection system is detected, then transmitted to the oscilloscope and displayed and recorded. Finally, the e exponent or deconvolution fitting is used to determine the natural radiation life of the energy level. The size of the magnetic field and the direction of polarization are properly adjusted. The fluorescence signal is oscillating, that is, the quantum beat attenuation signal is produced. Then, the quantum beat is produced. The curve is transformed by Fu Liye transform to obtain the quantum beat frequency and then determine the lad factor of the energy level. In the experiment, by using different excitation schemes, changing the observation channel and the delay time, eliminating the common excitation interference and ensuring the target energy level to be accurately excited. The effect of various physical effects (such as radiation trap effect, ultra radiation effect, quantum beat effect, saturation effect, collision effect, and flying out of view effect) on life measurement is eliminated. The life bound branching ratio is a kind of determination of transition probability and vibration. A reliable method of subdivision strength. In the aspect of branch ratio measurement, a hollow cathode lamp is used as the source of atomic or ion spectral lines. The emission spectrum is measured by a high resolution grating spectrometer. Then the transition spectrum is fitted and analyzed with the intensity ratio of the spectral line to determine the transition branch ratio. The specific contents of this paper include the following three parts: 1, using TR-LIF Methods and quantum beat spectroscopy, the Cr I 3d54p, 3d44s4p, 3d55p and 3d44s5p configurations are measured, and the lifetime of 35 odd parity energy levels and 43 odd parity energy levels between the energy levels are located between the 23305.0026-53782.78 cm-1 and the first measurements of 15 rad and 17 energy levels. The measured life values are in the 11.4-193 ns range. By comparing the g factor values with the g values in the different pure coupling methods, it is found that the coupling mode of the energy level is closer to the LS coupling. In addition, the branch ratio of the 8 chromium atom transition is determined by the atomic emission spectrum of the chromium hollow cathode lamp, and the transition probability and the oscillator strength of the 31 spectral lines are determined by the lifetime data. Two, The TR-LIF method is used to measure the natural radiation life of the 88 excited states of the 4f125d6s6p, 4f126s26p, 4f136s8s, 4f125d6s2,4f136s6p, 4f136s7p, 4f135d6p, and 4f136s8p configuration between 22791.176 and 48547.98cm-1, which are located between 22791.176 and 48547.98cm-1, and the lifetime values are between 15.4-7900. 26s6p, 4f125d6p, 4f125d6s, 4f125d2 and 4f126s2 configuration are located at the natural radiation life of 29 levels between 27294.79 and 65612.85 cm-1, the lifetime distribution is between 36.5-1000 ns, 22 of which belong to the first report. In addition, the position of the 15 Tm II levels is corrected. Three, the TR-LIF method is used to measure the configuration bits of the Eu 6. The natural radiation life of 6 parity energy levels between 39636.83 and 42530.91cm-1, of which 3 levels belong to the first measurement. Their life values are between 33-130 ns, and the lifetime error is within 10%. In summary, the natural radiation life of the chromium atom (Cr I), the Langde factor and the transition ratio are investigated and determined in this paper. In addition, the natural radiation life of thulium atom (Tm I), thulium monovalent ion (Tm II) and europium two valence ion (Eu III) energy level is also measured, and new atomic radiation and Lund factor parameters not reported in the literature are obtained. These atomic data are not only used to determine the abundance of chemical elements in the celestial bodies. It provides abundant spectral analysis data and has important scientific value for the research of nuclear fusion physics, atomic physics and plasma physics.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O562

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