785nmLD激发下Tm^(3+)/Ho^(3+):Y_2O_3纳米晶的上转换发光

Multicolor Upconversion Fluorescence of Tm^(3+)/Ho^(3+):Y_2O_3 Nanocrystals Produced by 785 nm Laser

以甘氨酸为燃烧剂,采用低温燃烧法制备了Tm3+,Ho3+共掺杂的Y2O3纳米晶粉末,通过X射线衍射和透射电子显微镜(TEM)对样品的结构、形貌和粒径进行了分析和表征.本文以785nm LD为激发光,研究了样品的上转换发光性质,实验结果得到了峰值波长为487nm(蓝色),548nm(绿色),659nm和695nm(红色)上转换发光.经过分析表明,上述发光分别指5F3→5I8(Ho3+)+1 G4→3 H6(Tm3+),(5F4,5S2)→5I8(Ho3+),5F5→5I8(Ho3+)和3F3→3 H6(Tm3+)跃迁.通过对上转换发光强度和激发光功率的关系研究,揭示出其均为双光子过程,并且能量传递上转换和激发态吸收是上转换发光的主要机制.由于其高效的上转换发光性能,该材料在荧光标记、三维立体显示等方面有着潜在的应用前景.

1%Tm3＋-doped,5%Ho3＋-doped and 1%Tm3＋,5%Ho3＋ co-doped Y2O3 nanocrystals were synthesized by solution combustion method.The particle size,structure and morphology of the samples were characterized by X-ray diffraction and transmission electron micrograph.Under 785 nm laser excitation,multicolor upconversion emissions near 487 nm（blue）,548 nm（green）,659 nm and 695 nm（red） were observed in Tm3＋,Ho3＋：Y2O3.These emission bands were assigned to be 5F3→5I8（Ho3＋）＋1G4→3H6（Tm3＋）,（5F4,5S2）→5I8（Ho3＋）,5F5→5I8（Ho3＋） and 3F3→3H6（Tm3＋）,respectively.The power dependence of upconverted emission intensity was measured to explain the upconversion mechanism.Several cross-relaxation energy transfer processes and excited state absorption（ESA） were found to be responsible for the observed upconversion emissions.