Eu^(3+):LaF_3纳米晶体-液体悬浮系统中荧光弛豫的局域场效应

Local-field Effect on Fluorescence Relaxation of Liquid Suspensions of Eu^(3+):LaF_3 Nanocrystals

为研究Eu3+:LaF3纳米晶体-液体悬浮系统中局域场效应对荧光辐射寿命的影响,首先用水热法成功制得了粒径均匀、分散性良好的Eu3+:LaF3纳米晶体,通过将其悬浮在各种液体介质中测出了532nm脉冲激光激发下Eu3+的5D0能级的荧光寿命,该能级的荧光衰减曲线呈明显的二阶指数衰减特征,对荧光寿命的分析表明其中快速荧光衰减部分源于纳米晶体表面附近的稀土离子。荧光衰减的长寿命部分与各种局域场效应理论模型中的最小二乘法拟合结果表明,忽略表面效应并考虑实际的量子效率时,实腔模型是解释本文的研究系统中荧光弛豫的局域场效应的最佳理论模型。

Well-dispersed Eu3＋：LaF3 nanocrystals were synthesized by simple hydrothermal method.In order to study local-field effect on the fluorescence radiative lifetime of Eu3＋：LaF3 nanocrystals suspended in various liquid media,the lifetime of 5D0 energy level was measured when the liquid suspension system was excited by 532 nm pulsed laser.It was found that the fluorescence decay presented the characteristics of second-order exponential decay,for which the faster decay origin from the ions at the interface of the nanocrystal and slower decay origin from the ions inside the nanocrystal.Ignoring surface effect and considerding actual quantum efficiency,we fitted these slower fluorescence lifetimes to various local-field models and found the real-cavity model is the best model for local-field effect of our system.