C_(3v)晶场中d~3离子吸收谱的理论研究

为了计算Cr~(3+)离子在C_(3v)对称晶场中的能谱,本文采用一种形式介于Richardson和Watson SCF波函数之间的束缚态d电子径向轨函;从Oh点群的Griffith标准基出发,用一种简便的方法,推出d~3系的C_(3v)点群强场谱项能量矩阵。由此计算了Ruby(Al_2O_3+Cr~(3+))和Cr_2O_3晶体中Cr~(3+)离子的吸收谱。在考虑扳——电耦合后,理论结果与实验符合甚好,从而解释了这两类晶体中Cr~(2+)吸收光谱的机制。这种计算方法既使拟合参数的数目大为减少,又使配位场理论计算格地理论化。

A THEORETICAL STUDY OF THE ABSORPTION SPECTRA OF d3~ IONS IN THE C_(3v)-CRYSTAL FIELD

In order to calculate the energy spectra of Cr3+ ions in C3v-symmetry crystal fields, a radial-orbit-function for the d-electrons in bounded ions, which has the form between the SCF wave-functions of Richardson and Watson, was used. In addition, the strong-field-term energy matrices of the d3 system for the C3v point group have been established by a simple and convenient method in which the Griffith standard bases of Oh point group are taken as the starting point. Then, the absorption spectra ( include the spin-allowed and spin-forbidden spectra) of Cr3+ ions in Ruby and Cr22O3 crystals have been calculated. The theoretical values, with a consideration of the vibronic, are in good agreement with the experemental. Thus, the mechanism of the absorpiton spectra of Cr3+ in those two crystals is well explained. In this scheme of calculation, the number of fitting parameters is considerably reduced and the calculations related to ligand field theory are strictly theoreticalized.