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晶场对称性方法研究稀土激光晶体的光谱和磁学性能

作　者: 陈学元
导　师: 张乾二；罗遵度
学　校: 中国科学院研究生院（福建物质结构研究所）
专　业: 物理化学
关键词: 晶场磁学性能群链矩阵元哈密顿量对称性方法研究电子能级结构稀土离子静电模型
分类号: O73
类　型: 博士论文
年　份: 1998年
下　载: 670次
引　用: 0次
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内容摘要

本文以Butler 的群链方案为基础分析了稀土离子掺杂的激光晶体的电子能级结构。首先以参数化的、静电模型哈密顿量来表示单电子晶场作用势, 根据群链分支定则, 激活离子在晶格中占据的位置对称性决定了晶场势展开项,即对称性允许存在的晶场势成分。利用群链理论, 属稀土离子4fⁿ 组态的波函数表示为以不可约表示（Butler 符号）标记的群链基波函数的线性组合; 借助Wigner-Eckart 定理和2jm 和3jm 因子的分解定律计算了晶场哈密顿的矩阵元; 根据点电荷模型和已知晶体结构数据, 利用点阵求和技术计算得到传统晶场参数B_kq 初值, 相应的非传统形式的群链参数初值则由两种方案下的转换关系求得; 这些初值通常作为非线性拟合晶场能级计算的初值, 系统的对称性畸变信息则反映在以同阶晶场参数的比值作为能级拟合的约束条件。晶场能级拟合分成两步进行:（1）对角化自由离子的参数哈密顿, 得到以纯LS 耦合谱项^2S+1L_J 为基的中间耦合波函数, 从而计算各谱项之间的约化矩阵元;（2）计算已知实验晶场能级数据的光谱项的晶场分裂矩阵元, 然后同时对角化并以最小二乘法程序拟合实验值, 从而得

全文目录

中文摘要  7-9
Abstract  9-11
Acknowledgement  11-12
Publications  12-13
Chapter 1 Introduction  13-22
  1.1 Historical outline  13-14
  1.2 Conventional crystal-field theory  14-19
  1.3 Introduction of the group-chain approach  19-22
Chapter 2 Group-chain scheme analysis  22-69
  2.1 Crystal-field Hamiltonian in the group-chain scheme  22-27
  2.2 The relationship between the CF parameters of two different schemes  27-30
  2.3 The matrix elements of the crystal-field Hamiltonian  30-33
  2.4 Crystal-field-level fitting  33-35
  2.5 The Zeeman interaction, Schottky specific heat and paramagnetic susceptibility  35-39
  2.6 Study of the relative emission intensity and polarization  39-48
    2.6.1 The matrix element for the electric-dipole(ED) transition  39-45
    2.6.2 Fitting the odd crystal-field parameters  45-46
    2.6.3 Selection rules  46-48
  Appendixes  48-69
    Appendix 2.1 The commonly used intermediate-coupling wavefunctions of RE ions  48-50
    Appendix 2.2 Reduced matrix elements of U~((k)) between terms for RE~(3+) ion  50-52
    Appendix 2.3 The matrix elements of CF Hamiltonian for D_3 site-symmetry with the group-chain SO_3(?)O(?)D_3  52-57
    Appendix 2.4 The matrix elements of CF Hamiltonian for S_4 site-symmetry with the group-chain O_3(?)O_h(?)T_d(?)D_(2d)(?)S_4  57-60
    Appendix 2.5 The matrix elements of CF Hamiltonian for D_(2d) site-symmetry with the gropy-chain O_3(?)O_h(?)T_d(?)D_(2d)  60-63
    Appendix 2.6 The least-squares fit program for Er~(3+):LiYF_4 with S_4 site-symmetry  63-69
Chapter 3 The application of group-chain scheme analysis  69-143
  3.1 Er~(3+):LiYF_4  69-78
    3.1.1 Introduction  69
    3.1.2 Energy-level-fitting and wavefunctions  69-75
    3.1.3 The Zeeman interaction  75-78
  3.2 Nd~(3+):LiYF_4  78-83
    3.2.1 Introduction  78
    3.2.2 Energy-level-fitting and wavefunctions  78-80
    3.2.3 The Zeeman interaction  80-83
  3.3 Tm~(3+):LiYF_4  83-94
    3.3.1 Introduction  83
    3.3.2 Energy-level-fitting and wavefunctions  83-87
    3.3.3 The Zeeman interaction, Schottky specific heat and magnetic susceptibility  87-90
    3.3.4 Study of the polarization and relative intensities of emissions  90-94
  3.4 Tm~(3+):YVO_4  94-109
    3.4.1 Introduction  94
    3.4.2 Energy-level-fitting and wavefunctions  94-97
    3.4.3 The Zeeman interaction, Schottky specific heat and magnetic susceptibility  97-101
    3.4.4 Judd-Ofelt parameter analysis  101-104
    3.4.5 Fluorescence dynamics of Tm~(3+) ions in YVO_4 crystal  104-109
  3.5 Nd~(3+):YVO_4  109-116
    3.5.1 Introduction  109
    3.5.2 Energy-level-fitting and wavefunctions  109-111
    3.5.3 Study of the polarization and relative intensities of emissions  111-116
  3.6 Nd~(3+):YAl_3(BO_3)_4  116-130
    3.6.1 Introduction  116-117
    3.6.2 Energy-level-fitting and wavefunctions  117-121
    3.6.3 The Zeeman interaction  121-123
    3.6.4 Study of the line-to-line fluorescence emissions from ~4F_(3/2)  123-130
  Appendixes  130-143
    Appendix 3.1 Wavefunctions of crystal-field energy levels (O_3(?)O_h(?)T_d(?)D_(2d)(?)S_4) for Er:YLF  130-132
    Appendix 3.2 Wavefunctions of crystal-field energy levels (O_3(?)Oh(?)Td(?)D_(2d)(?)S4) for Nd:YLF  132-135
    Appendix 3.3 Wavefunctions for crystal-field energy levels (O_3(?)O_h(?)T_d(?)D_(2d)) for Tm:YLF  135-137
    Appendix 3.4 Wavefunctions for crystal-field energy levels (O_3(?)O_h(?)T_d(?)D_(2d)) for Tm~(3+):YVO_4  137-140
    Appendix 3.5 Wavefunctions for crystal-field energy levels (O_3(?)O_h(?)T_d(?)D_(2d)) for Nd~(3+):YVO_4  140-141
    Appendix 3.6 Wavefunctions for crystal-field energy levels (SO_3(?)O(?)D_3) for NYAB  141-143
Chapter 4 Concluding remarks  143-149
  4.1 Brief summary  143-144
  4.2 Discussion of two-electron CF effects  144-146
  4.3 Discussion of the ED intensity calculation  146-148
  4.4 Future work  148-149
References  149-153

晶场对称性方法研究稀土激光晶体的光谱和磁学性能

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