摘要
在12K的温度下,测量了水热法生长的K2YF5∶Tm3+单晶的发射和吸收光谱,分析了高掺杂样品中Tm3+离子间的交叉弛豫行为。用最小二乘法对实验能级进行拟合计算,得到了较好的均方差:18cm-1。此外,文中还给出了K2YF5∶Tm3+共振激发下1D2和1G4能级寿命的测量结果,并分析和讨论了掺杂量对能级寿命的影响。
Rare earth ions doped inorganic materials have been extensively applied to many fields, such as display techniques, laser medium, and fiber communications. Trivalent thulium (Tm3+) in different hosts exhibits interesting optic and magnetic properties that are amenable to convenient experimental and theoretical studies. The fluoride compound doped with Tm3+ has been identified as an excellent candidate of laser material, due to its high efficiency, narrow line widths, and unusually large transition cross sections. In addition, the crystal structure of the fluoride compound permits greater doping concentrations of larger rare earth ions than other widely used host materials such as yttrium aluminum garnet and yttrium scandium garnet. For many applications, it is important to know the detailed energy level scheme of RE3+ in the appropriate host matrix. However, wellestablished investigations of the energy level scheme of Tm3+ ion in various host matrices are rather scarce. Detailed characterization of the interactions effective in the formation of the energy level scheme of the Tm3+ ion had been carried out mostly for the simple fluorides and oxide matrices. In addition, the maximum degeneracy of 91, which is rather low for an RE3+ ion, can be treated theoretically and by computational means easily as a whole without any truncations. In this paper the experimental results of absorption and emission spectra of K2YF5∶Tm3+ at 12K were reported. The optical data were interpreted in terms of the C2v point symmetry of the Tm3+ site in the K2YF5 matrix using the multipolar and group theoretical selection rules for electronic transitions. The Stark energy levels of ground state 3H6 and excited states 1D2,1G4,3F2,3F3 and 3F4 were assigned clearly. The experimental energy levels are compared with those of calculated by a phenomenological model, in which the Hamiltonian includes the electrostatic, spinorbit interactions and crystal field interactions. The simulated treatment of the free ion and crystal field interactions within 4f12 electron configuration yielded a satisfactory agreement with the experimental values of 32 Stark components, with a quite small root mean square deviation of 18cm-1. In older to acquire the information of crystal field effect, the parameters S and Sk were introduced.In addition, decay curves of 1D2 and 1G4 emissions in the samples with different Tm3+ doping friction were discussed. Cross relaxation mechanisms have been used to explain the variations of the lifetimes.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2003年第5期505-511,共7页
Chinese Journal of Luminescence
基金
国家自然科学基金(10074061)
教育部跨世纪优秀人材培养计划基金资助项目
