Tm^(3+)离子掺杂的钨酸钇钠晶体中浓度猝灭效应的研究

Investigation of concentration quenching effect in Tm^(3+)-doped NaY(WO_4)_2 crystal

测量了Tm3+离子不同浓度(0.5at.%,3at.%,5at.%)掺杂的NaY(WO4)2晶体在800nm激光二极管激发下的上转换发射光谱.结合吸收谱、荧光谱和由Judd-Ofelt理论计算的光谱参数,详细分析了Tm3+:NaY(WO4)2晶体中上转换能量传递机理和离子浓度对上转换发射的影响.讨论了四种影响上转换发光效率的离子间相互作用机理:3H5+1G4→3H6+1D2,3H5+3H5→3H6+3F3,1G4+3H6→3F4+3F3,1G4+3H6→3F3+3F4,并根据Miyakawa-Dexter理论定量计算了各过程的发生概率.论证了交叉弛豫和共协上转换等浓度猝灭效应是影响Tm3+离子蓝色上转换荧光发射效率的主要因素.

Upconversion blue emissions of Tm^3＋ ions with different doping （0.5at. %, 3 at. %, 5 at. % ） in NaY（WO4 ）2 crystals are investigated under 800nm diode laser excitation. The upeonversion mechanism and the dependence of upeonversion efficiency on ion concentration are analyzed with respect to the absorption spectra, fluorescence spectra, and parameters calculated by Judd- Ofelt theory. Four ion-ion interaction processes： 3H5 ＋ 1G4→ 3H6 ＋ 1D2, 3H5 ＋ 3H5→3H6 ＋ 3F3, 1G4 ＋ 3H6→3F4 ＋ 3F3, 1G4 ＋ 3H6→3F3 ＋ 3F4, which influence the upeonversion dominantly in Tm^3＋ heavy-doped system, are demonstrated theoretically and experimentally. The results indicate that cross-relaxation and cooperative upeonversion are the dominant processes affecting the blue emission efficiency.