红宝石吸收宽带的强度

红宝石晶体中Cr³⁺与六个近邻O^2-组成一个有严重畸变的正八面体,因而高阶奇晶场与一阶奇晶场有相同的数量级。由于红宝石中Cr³⁺的格位近似保持C_3v对称,T_2u型的高阶场非常小,可以忽略,但T_1u,A_2u型高阶晶场对红宝石吸收谱强度则原则上不能予以忽视,对于Y带和U^⊥带,高阶场有显著贡献,但对U^‖带,所产生的强度非常小。本文考虑了格点奇对称振动对U,Y带强度的贡献,发现U^‖带主要是奇振动与电子耦合产生的吸收谱。由此出发,讨论了红宝石宽带振子强度、带形等问题,得到了与实验相符合的结果。

ON THE INTENSITY OF THE ABSORPTION BANDS OF RUBY

In ruby a Cr³⁺ ion and its six nearest neighbouring O^2- ions form a heavily distorted octahedron. Consequently, the magnitude of odd crystal field of the higher order is comparable with the first-order odd field. Because of the site group of Cr³⁺ ion in ruby approximately retains C_3v symmetry, the higher-order crystal field component of T_2u type is very small and can be neglected, but those of T_1u type and A_2u type must be taken into account. The higher-order odd field components make appreciable contribution to Y band and U^⊥ band, but their contribution to U^‖ band is negligible.The intensities of U^‖ band and Y band are discussed with proper attention paid to the odd vibrations of ions. It has been concluded that the U band absorption is mainly produced through the coupling of odd vibrations with electrons. With this point of view, the oscillator strength, the dichroism, the band shape, etc., of the absorption bands of ruby are analysed. The results are in good agreement with experimental data.