反应时间对CMC/Tb纳米粒子结构及荧光性能的影响

Effect of Reaction Time on Structure and Fluorescence Properties of CMC / Tb Nanoparticles

在不同反应时间下制备了CMC/Tb纳米复合物,并通过SEM、FT-IR、XPS、UV-Vis及荧光光谱考察了这些复合物的形貌、结构及其荧光性能.结果表明:CMC/Tb复合物为球形颗粒状的粒子,其尺寸为100 nm左右;不同反应时间下Tb3+离子与CMC键合方式相似,都与CMC分子链上的—OH、—COO-以及—COC中O原子发生化学反应,但由于反应过程中CMC大分子的构象存在动态平衡,使得产物中的配位结构略有差异;CMC为主要的光能量吸收体,能有效敏化Tb3+离子发射窄的5D4→7F6(489 nm)、5D4→7F5(545 nm)、5D4→7F4(584 nm)和5D4→7F3(619 nm)电子轨道跃迁特征峰,其最强的5D4→7F5跃迁绿色荧光发射特征峰的半峰宽小于10 nm,而其强度随反应时间延长而上下波动,并在75 min后趋于平稳.

CMC/Tb nano-particles were synthesized in different reaction times .Then, the morphology, structure and fluorescence properties of the complexes were investigated by means of SEM , FT-IR and XPS and by using UV-Vis spectra and PL spectra .The results show that （1） CMC/Tb nano-particles are spherical particles and the parti-cle sizes are around 100 nm;（2） for different reaction times, Tb3＋ions bind CMC in a similar way, specifically, all the Tb3＋ions react with the atom O of —OH,—COO and—COC groups on CMC chain;（3） however, the co-ordination structures of CMC/Tb nano-particles are different due to the dynamic equilibrium of CMC conformation during the reaction;（4） CMC acts as the primary light energy absorber and it can effectively sensitize Tb 3＋ions to make the CMC/Tb nano-particles exhibit four characteristic narrow emission bands , namely, 5D4→7F6（489 nm）, 5D4→7F5（545 nm）, 5D4→7 F4 （584 nm） and 5D4→7 F3 （619 nm）; and （5） in the four emission bands, the 5 D4→7 F5 transition with the green emission is the most prominent band of the Tb 3＋ions, moreover, its half-peak width is less than 10 nm, and its intensity fluctuates with the reaction time and becomes steady after 75 minutes.