晶体Zn(antipyrine)_2(NO_3)_2∶VO^(2+)的EPR谱及光吸收谱的理论研究

Theoretical Investigation of EPR Spectra and Optical Absorption Spectra for Zn(antipyrine)_2(NO_3)_2∶VO^(2+) Crystal

由于硝酸钒锌二安替比林晶体[Zn(antipyrine)2(NO3)2∶VO2+]中配体O2-的自旋-轨道耦合参量0pζ≈150cm-1与中心过渡族3d1离子V4+的ζ0d≈248 cm-1相差不太大,故配体的自旋-轨道耦合参量0pζ对电子顺磁共振(EPR)谱和光吸收谱的贡献必须考虑。采用双自旋-轨道耦合参量模型和相关的晶体场能级公式,计算了Zn(antipyrine)2(NO3)2∶VO2+晶体的EPR谱和光吸收谱,所得理论结果与实验发现很好符合;确定了该晶体的局域对称结构沿C4轴的四角畸变约为0.45 nm;计算发现,较大的κ值说明VO2+中未配对的s电子对超精细结构常数有较大的贡献。并对上述这些结果的合理性进行了讨论。

Since the spin-orbit coupling parameter （ζp^0≈150cm^-1） of ligand O^2- is close to that （ζd^0≈248） of the central 3d^1 ion in Zn（antipyrine）2 （NO3）2 ：VO^2＋ crystal, the effect of the spin-orbit coupling parameter ζp^0 on the electron paramagnetic resonance （EPR） spectra and optical absorption spectra should be taken into account. Therefore, the EPR spectra and optical absorption spectra of VO^2＋ in Zn（antipyrine）2 （NO3）2 single crystal are calculated based on the two-spin-orbit-coupling parameter model and correlative formulae of the crystal-field energy levels. Theoretical results of EPR spectra and optical absorption spectra of Zn（antipyrine）2 （NO3）2：VO^2＋ are in good agreement with experimental findings. According to the present investigation, the value of this tetragonal distortion of the local symmetry along C4 axis is 0.45 nm. The calculated result shows that the large value of κ indicates a large contribution to the hyperfine constant by the unpaired s-electron. The reasonableness of these results is discussed.