Ba_2MgGe_2O_7∶Cr^(4+)晶体中荷移激发态对g因子贡献的研究  

Study on the Contribution of the Charge Transfer Excited States in Ba_2MgGe_2O_7∶Cr^(4+) Crystal to g Factor

作　　者：吴晓轩[1,2,3] 郑文琛[2,3] 

机构地区：[1]中国民航飞行学院物理教研室,四川广汉618307 [2]四川大学材料科学系,四川成都610064 [3]中国科学院国际材料物理中心,辽宁沈阳110016

出　　处：《光谱学与光谱分析》2007年第1期8-11,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(10274054);民航总局民航飞行技术与飞行安全科研基地项目资助

摘　　要：文章建立了立方四面体3d2络合物g因子的完全高阶微扰公式。在这个公式中,除了与d—d跃迁光谱(晶场激发态)有关的晶场(CF)机制的贡献(包括近年发展的双旋-轨耦合参量模型)外,与电荷转移光谱(荷移激发态)有关的荷移(CT)机制的贡献也被考虑。将这个公式应用于Ba2MgGe2O7∶Cr4+晶体平均g因子的计算,发现理论计算值与实验值很好的一致,同时,荷移机制对g移动Δg(=g-2.002 3)的贡献ΔgCT在符号上与晶场机制的贡献ΔgCF相反,而在大小上约为晶场机制贡献的38%。因此,在对高价态过渡金属离子络合物的g因子计算时应考虑CF机制和CT机制的贡献。A complete high-order perturbation formula of g factor for cubic 3d2 MX4 clusters was established. In the formula, not only the contributions of the crystal-field （CF） mechanism （which is related to the CF excitations） to the g-shift △g（=g g,）, but also the contributions of the charge-transfer （CT） mechanism （related to CT excitations） were considered. Using the formula, the g factor of Ba2MgGe2O7 ： Cr^4＋ was calculated. The result was in agreement with the observed value. It was found that the calculated Agcr due to the charge-transfer mechanism is opposite in sign and about 38% in magnitude, compared with the calculated △gcF due to the crystal-field mechanism. So, for a high valence 3d^m ion in crystals, the reasonable explanation of g factor should take into account the contributions of both crystal-field and charge-transfer mechanisms.

关 键 词：电子顺磁共振 G因子 荷移机制 晶体场和配位场理论 Ba2MgGe2O7晶体 

分 类 号：O482.5[理学—固体物理]