硅酸钡铜的光吸收谱和EPR谱

本文报道水热合成硅酸钡铜(BaCuSi_4O_(10))的光吸收谱和EPR谱。EPR测量表明,在硅酸钡铜中,Cu~(2 )离子位置有轴对称性。在这种对称性下,一般只能观察到三条Cu~(2 )离子的吸收谱带,但在BaCuSi_4O_(10)的吸收谱中却观察到了四条。这一矛盾用~2Eg激发态的动态Jahn-Teller效应来解释。本文提出的~2Eg和~2A_1g能级的相对次序与文献[2]的相反,文中对这一问题作了详细的分析。跃迁频率和g因子的计算值在实验误差范围内与观测值一致。

OPTICAL ABSORPTION AND EPR SPECTRA OF BaCuSi_4O_(10)

Reported in this paper are the optical absorption and EPR spectra of Cu~(2 ) ions in a hydrothermally synthetic silicate (BaCuSi_4O_(10)),which is known to be isostructural wlth the natural mineral gillespite. EPR measurements indicate that the electronic environment of Cu~(2 ) ion in BaCuSi_4O_(10) is of axial symmetry. At a glance,this contradicts the optical absorption spectrum in which four bands are observed. The apparent inconsistency between the EPR and the optical absorption measurements has been attributed to the dynamical Jahn-Teller effect of the excited ~2Eg state.According to this work,the relative order of the ~2Eg and ~2A_(1g) states is in contradiction to that proposed by Clark and Burns. The reason for this is discussed,Three parameters, two crystal-field parameters and a spin-orbit coupling parameter have been involved in the calculation. The results for optical transition frequencies and g-factors are in good agreement with experimental values.