络合物中掺杂过渡金属离子光谱和局域结构性质的研究

Electron paramagnetic resonance (EPR) is a powerful tool to investigate local structures, electronic and spin levels, etc, for TM ions doped into crystal and compounds. Up to now, the theoretical explanations to the EPR experimental results have some imperfections. For example, the influences of the ligand orbital and spin-orbit coupling interactions were not taken into account; the simple second-order perturbation g formulas were adopted by introducing various adjustable parameters; failing to establish uniform theoretical relationships between EPR spectra and local structures of the systems. In order to overcome the above shortcomings and to better studied the energy levels and the local structure properties (particularly the relationship between these properties and optical and EPR spectra) more exactly. In this project, the calculated formulas and programs of the spectroscopic parameters for the TM ions are established from a unified physical model, in these formulas, not only the contribution due to the ligand spin-orbit coupling coefficients and configuration interaction, but also these due to the admixtures of various energy levels and the covalency effect (which were usually neglected in the previous papers) are included, and the energy denominator are determined from the local structures of the impurity centers and superposition model. The related parameters (e.g., crystal field parameters，energy level mixing coefficients and molecular orbital coefficients) are correlated with the local structures and the optical spectral data of the systems. Thus, these experimental spectral parameters are reasonable and uniformly interpreted.

电子顺磁共振（EPR）谱是研究掺杂过渡金属离子局部结构、电子态和自旋能级等的有效手段。实验工作者在EPR参量研究方面存在着诸如忽略了配体轨道和自旋-轨道耦合的贡献、直接采用简单的二阶微扰公式、利用较多的可调参量、未能将EPR谱和光谱与掺杂离子所处局部结构信息相联系等问题。为了更好地研究络合物中掺杂离子的能级和局域结构性质，以及这些性质与杂质中心EPR谱和光谱的关系。本项目从统一的物理图像出发，建立络合物中掺杂离子谱学参量的理论模型、计算公式及程序，其中包含前人通常忽略的自旋-轨道耦合、组态相互作用、不同能级混合以及共价效应等因素的贡献，能量分母由杂质中心的局部结构参量和重叠模型确定，将一些重要的参数（如晶场参量、能级混合系数以及分子轨道系数等）与络合物中杂质中心的局部结构和光谱数据相联系，从而对这些体系的光谱参量作出统一和合理的理论解释。

基于配位场理论，建立了掺杂过渡金属离子的EPR参量的高阶微扰公式并应用于一些典型的体系。具体为：.1）基于四角伸长八面体中低自旋(S = 1/2)3d7离子的EPR参量高阶微扰公式，在计算HCoO2和LiCoO2中掺杂Ni3+的EPR-g因子的基础上获得其局域结构信息。研究表明，对HCoO2 (和LiCoO2) 中掺杂Ni3+离子，Jahn-Teller效应使配体八面体沿[001]轴分别伸长2.57% (和1.6%)。.2）基于3d1离子在四角压缩八面体对称下EPR参量的高阶微扰公式，研究了MgKPO4•6H2O中V4+中心的光谱和EPR参量，并获得其局域结构，发现平行和垂直于C4-轴的杂质-配体离子键长分别为R|| ≈ 1.846 Å和R⊥ ≈ 2.032 Å..3）研究了Zn(C3H3O4)2(H2O)2: Cu2+的EPR参量，计算中考虑了d轨道基态波函数的混合。计算表明，杂质Cu2+离子周围的局域结构分别为Rx ≈ 0.1872 nm, Ry ≈ 0.2033 nm, Rz ≈ 0.2292 nm。.4) 基于正交伸长八面体对称下3d9离子EPR参量的高阶微扰公式，通过分析(CH3)2NH2Al(SO4)2•6H2O:Cu2+的EPR参量，获得了局域结构信息。由于Jahn-Teller效应，对杂质Cu2+离子中心I和II，位于平面Cu2+- O2-键沿X-和Y-轴发生相对键长变化分别为δR (≈ 0.033和0.063 Ǻ)，而沿C2轴的Cu2+- O2-键分别发生相对伸长ΔZ (≈ 0.058和0.052 Å)。.5）利用伸长八面体中3d9离子自旋哈密顿参量高阶微扰公式分析了Zinc 1-malate trihydrate:Cu2+的EPR参量。计算表明， Jahn-Teller效应导致杂质中心[CuO6]10-的键长R|| ≈ 0.2157 nm，R⊥ ≈ 0.2058 nm，表现为一个伸长八面体。.6）基于四角伸长八面体中3d9离子的高阶微扰公式，研究了铝铅硼酸玻璃体和ZnAl2O4中Cu2+离子的EPR参量。计算表明，对铝铅硼酸玻璃体和ZnAl2O4中的Cu2+离子中心，由于Jahn-Teller效应，Cu2+离子附近的O2-八面体沿C4轴分别发生相对伸长约19.2％和3.2％，同时确定了Cu2+离子中心的A||符号为负及A⊥为正。