利用晶体场理论和不可约张量方法,采用中间态耦合及新的参数公式,对稀土离子能级精细结构及波函数进行理论计算,给出Er3+ 、nd3+ 两种重要稀土离子精细结构能级位置. 实验上测定了的500~950 nM 吸收光谱,获得了与理论相一致的精细结构能级,并讨论了新波长激光的产生机制.This paper reports an outline of theoreticalcalculation for the fine-struc- ture energy levels and their wavefunctions ofrare earth ions, based on the irreducible tensor technique and crystal-field theory as w ellas the interm ediate coupling w ith new param eterized form ula.For tw o im portant rare earth ions, Nd3+ and Er3+ , the fine-structure energy levels are theoretically determ ined.Experim entally, the absorption spectra from 500 nm to 950 nm w ere carried out for the Nd3+ ∶Er3+ ∶YAlO3 laser crystal.The fine-structure energy levels w ere therefore experim entally obtained, and they are in good agreem ent w ith the theoretical ones.Finally, the generation m echanism ofnew w avelength laser is also discussed.国家自然科学基金!(69878023);福建省自然科学基金重点课题基金!(A97009